Initial data commit

Task/Semiprime/00-META.yaml

@@ -0,0 +1,3 @@
+---
+from: http://rosettacode.org/wiki/Semiprime
+note: Prime Numbers

Task/Semiprime/00-TASK.txt

@@ -0,0 +1,28 @@
+Semiprime numbers are natural numbers that are products of exactly two (possibly equal) [[prime_number|prime numbers]]. 
+
+
+'''Semiprimes'''   are also known as:
+:::*   '''semi-primes'''
+:::*   '''biprimes'''
+:::*   '''bi-primes'''
+:::*   ''' ''2-almost'' '''   primes
+:::* &nbsp; or simply: &nbsp; ''' ''P<sub>2</sub> '' '''
+
+
+
+;Example: 
+   <big> 1679  =  23 &times; 73 </big> 
+
+(This particular number was chosen as the length of the [http://en.wikipedia.org/wiki/Arecibo_message Arecibo message]). 
+
+
+;Task:
+Write a function determining whether a given number is semiprime.
+
+
+;See also:
+* The Wikipedia article: &nbsp;[[wp:Semiprime|semiprime]].
+* The Wikipedia article: &nbsp;[[wp:Almost_prime|almost prime]].
+* The OEIS sequence: &nbsp;[[oeis:A001358|A001358: semiprimes]]&nbsp; which has a shorter definition: ''the product of two primes''.
+<br><br>
+

Task/Semiprime/11l/semiprime.11l

@@ -0,0 +1,12 @@
+F is_semiprime(=c)
+   V a = 2
+   V b = 0
+   L b < 3 & c != 1
+      I c % a == 0
+         c /= a
+         b++
+      E
+         a++
+   R b == 2
+
+print((1..100).filter(n -> is_semiprime(n)))

Task/Semiprime/360-Assembly/semiprime.360

@@ -0,0 +1,71 @@
+*        Semiprime                 14/03/2017
+SEMIPRIM CSECT
+         USING  SEMIPRIM,R13       base register
+         B      72(R15)            skip savearea
+         DC     17F'0'             savearea
+         STM    R14,R12,12(R13)    save previous context
+         ST     R13,4(R15)         link backward
+         ST     R15,8(R13)         link forward
+         LR     R13,R15            set addressability
+         LA     R10,PG             pgi=0
+         LA     R8,0               m=0
+         L      R6,=F'2'           i=2
+       DO WHILE=(C,R6,LE,=F'100')  do i=2 to 100
+         ST     R6,N                 n=i
+         LA     R9,0                 f=0
+         LA     R7,2                 j=2
+LOOPJ    EQU    *                    do j=2 while f<2 and j*j<=n
+         C      R9,=F'2'               if f<2
+         BNL    EXITJ                  then exit do j
+         LR     R5,R7                  j
+         MR     R4,R7                  *j
+         C      R5,N                   if j*j<=n
+         BH     EXITJ                  then exit do j
+LOOPK    EQU    *                      do while n mod j=0
+         L      R4,N                     n
+         SRDA   R4,32                    ~
+         DR     R4,R7                    /j
+         LTR    R4,R4                    if n mod <>0
+         BNZ    EXITK                    then exit do j
+         ST     R5,N                     n=n/j
+         LA     R9,1(R9)                 f=f+1
+         B      LOOPK                  enddo k
+EXITK    LA     R7,1(R7)               j++
+         B      LOOPJ                enddo j
+EXITJ    L      R4,N                 n
+       IF C,R4,GT,=F'1' THEN         if n>1 then
+         LA     R2,1                   g=1
+       ELSE     ,                    else
+         LA     R2,0                   g=0
+       ENDIF    ,                    endif
+         AR     R2,R9                +f
+       IF C,R2,EQ,=F'2' THEN         if f+(n>1)=2 then
+         XDECO  R6,XDEC                edit i
+         MVC    0(5,R10),XDEC+7        output i
+         LA     R10,5(R10)             pgi=pgi+10
+         LA     R8,1(R8)               m=m+1
+         LR     R4,R8                  m
+         SRDA   R4,32                  ~
+         D      R4,=F'16'              m/16
+       IF LTR,R4,Z,R4 THEN             if m mod 16=0 then
+         XPRNT  PG,L'PG                  print buffer
+         MVC    PG,=CL80' '              clear buffer
+         LA     R10,PG                   pgi=0
+       ENDIF    ,                      endif
+       ENDIF    ,                    endif
+         LA     R6,1(R6)             i++
+       ENDDO    ,                  enddo i
+         XPRNT  PG,L'PG            print buffer
+         MVC    PG,=CL80'..... semiprimes'  init buffer
+         XDECO  R8,XDEC            edit m
+         MVC    PG(5),XDEC+7       output m
+         XPRNT  PG,L'PG            print buffer
+         L      R13,4(0,R13)       restore previous savearea pointer
+         LM     R14,R12,12(R13)    restore previous context
+         XR     R15,R15            rc=0
+         BR     R14                exit
+N        DS     F                  n
+PG       DC     CL80' '            buffer
+XDEC     DS     CL12               temp
+         YREGS
+         END    SEMIPRIM

Task/Semiprime/ALGOL-68/semiprime.alg

@@ -0,0 +1,38 @@
+# returns TRUE if n is semi-prime, FALSE otherwise            #
+#         n is semi prime if it has exactly two prime factors #
+PROC is semiprime = ( INT n )BOOL:
+     BEGIN
+         # We only need to consider factors between 2 and     #
+         # sqrt( n ) inclusive. If there is only one of these #
+         # then it must be a prime factor and so the number   #
+         # is semi prime                                      #
+         INT factor count := 0;
+         FOR factor FROM 2 TO ENTIER sqrt( ABS n )
+         WHILE IF n MOD factor = 0 THEN
+                   factor count +:= 1;
+                   # check the factor isn't a repeated factor #
+                   IF n /= factor * factor THEN
+                       # the factor isn't the square root     #
+                       INT other factor = n OVER factor;
+                       IF other factor MOD factor = 0 THEN
+                           # have a repeated factor           #
+                           factor count +:= 1
+                       FI
+                   FI
+               FI;
+               factor count < 2
+         DO SKIP OD;
+         factor count = 1
+     END # is semiprime # ;
+
+# determine the first few semi primes                          #
+print( ( "semi primes below 100: " ) );
+FOR i TO 99 DO
+    IF is semi prime( i ) THEN print( ( whole( i, 0 ), " " ) ) FI
+OD;
+print( ( newline ) );
+print( ( "semi primes below between 1670 and 1690: " ) );
+FOR i FROM 1670 TO 1690 DO
+    IF is semi prime( i ) THEN print( ( whole( i, 0 ), " " ) ) FI
+OD;
+print( ( newline ) )

Task/Semiprime/ALGOL-W/semiprime.alg

@@ -0,0 +1,19 @@
+begin % find some semi-primes - numbers with exactly 2 prime factors %
+    logical procedure isSemiPrime( integer value v ) ;
+    begin
+        integer a, b, c;
+        a := 2; b := 0; c := v;
+        while b < 3 and c > 1 do begin
+            if c rem a = 0 then begin
+                c := c div a;
+                b := b + 1
+                end
+            else a := a + 1;
+        end while_b_lt_3_and_c_ne_1 ;
+        b = 2
+    end isSemiPrime ;
+
+    for x := 2 until 99 do begin
+        if isSemiPrime( x ) then writeon( i_w := 1, s_w := 0, x, " " )
+    end for_x
+end.

Task/Semiprime/ASIC/semiprime.asic

@@ -0,0 +1,23 @@
+REM Semiprime
+PRINT "Enter an integer ";
+INPUT N
+N = ABS(N)
+
+Count = 0
+IF N >= 2 THEN
+  FOR Factor = 2 TO N
+    NModFactor = N MOD Factor
+    WHILE NModFactor = 0
+      Count = Count + 1
+      N = N / Factor
+      NModFactor = N MOD Factor
+    WEND
+  NEXT Factor
+ENDIF
+
+IF Count = 2 THEN
+  PRINT "It is a semiprime."
+ELSE
+  PRINT "It is not a semiprime."
+ENDIF
+END

Task/Semiprime/AWK/semiprime.awk

@@ -0,0 +1,28 @@
+# syntax: GAWK -f SEMIPRIME.AWK
+BEGIN {
+    main(0,100)
+    main(1675,1680)
+    exit(0)
+}
+function main(lo,hi,  i) {
+    printf("%d-%d:",lo,hi)
+    for (i=lo; i<=hi; i++) {
+      if (is_semiprime(i)) {
+        printf(" %d",i)
+      }
+    }
+    printf("\n")
+}
+function is_semiprime(n,  i,nf) {
+    nf = 0
+    for (i=2; i<=n; i++) {
+      while (n % i == 0) {
+        if (nf == 2) {
+          return(0)
+        }
+        nf++
+        n /= i
+      }
+    }
+    return(nf == 2)
+}

Task/Semiprime/Action-/semiprime.action

@@ -0,0 +1,28 @@
+BYTE FUNC IsSemiPrime(INT n)
+  INT a,b
+
+  a=2 b=0
+  WHILE b<3 AND n#1
+  DO
+    IF n MOD a=0 THEN
+      n==/a b==+1
+    ELSE
+      a==+1
+    FI
+  OD
+  IF b=2 THEN
+    RETURN(1)
+  FI
+RETURN(0)
+
+PROC Main()
+  INT i
+
+  PrintE("Semiprimes:")
+  FOR i=1 TO 500
+  DO
+    IF IsSemiPrime(i) THEN
+      PrintI(i) Put(32)
+    FI
+  OD
+RETURN

Task/Semiprime/Ada/semiprime.ada

@@ -0,0 +1,21 @@
+with Prime_Numbers, Ada.Text_IO;
+
+procedure Test_Semiprime is
+
+   package Integer_Numbers is new
+     Prime_Numbers (Natural, 0, 1, 2);
+   use Integer_Numbers;
+
+begin
+   for N in 1 .. 100 loop
+      if Decompose(N)'Length = 2 then -- N is a semiprime;
+	 Ada.Text_IO.Put(Integer'Image(Integer(N)));
+      end if;
+   end loop;
+   Ada.Text_IO.New_Line;
+   for N in 1675 .. 1680 loop
+      if Decompose(N)'Length = 2 then -- N is a semiprime;
+	 Ada.Text_IO.Put(Integer'Image(Integer(N)));
+      end if;
+   end loop;
+end Test_Semiprime;

Task/Semiprime/Arturo/semiprime.arturo

@@ -0,0 +1,5 @@
+semiPrime?: function [x][
+    2 = size factors.prime x
+]
+
+print select 1..100 => semiPrime?

Task/Semiprime/AutoHotkey/semiprime.ahk

@@ -0,0 +1,55 @@
+SetBatchLines -1
+k := 1
+loop, 100
+{
+	m := semiprime(k)
+	StringSplit, m_m, m, -
+		if ( m_m1 = "yes" )
+			list .= k . " "
+	k++
+}
+MsgBox % list
+list :=
+;===================================================================================================================================
+k := 1675
+loop, 5
+{
+	m := semiprime(k)
+	StringSplit, m_m, m, -
+		if ( m_m1 = "yes" )
+			list1 .= semiprime(k) . "`n"
+		else
+			list1 .= semiprime(k) . "`n"
+	k++
+}
+MsgBox % list1
+list1 :=
+;===================================================================================================================================
+; The function==========================================================================================================================
+semiprime(k)
+{
+		start := floor(sqrt(k))
+				loop, % floor(sqrt(k)) - 1
+					{
+							if ( mod(k, start) = 0 )
+								new .= floor(start) . "*" . floor(k//start) . ","
+						start--
+					}
+		
+		StringSplit, index, new, `,
+		
+			if ( index0 = 2 )
+				{
+					StringTrimRight, new, new, 1
+					StringSplit, 2_ind, new, *
+						if (mod(2_ind2, 2_ind1) = 0) && ( 2_ind1 != 2_ind2 )
+							new := "N0- " . k . "  -  " . new
+						else
+							new := "yes- " . k . "  -  " . new
+				}
+			else
+				new := "N0- " . k . "  -  " . new
+return new
+}
+;=================================================================================================================================================
+esc::Exitapp

Task/Semiprime/BASIC256/semiprime.basic

@@ -0,0 +1,19 @@
+function semiprime$ (n)
+    a = 2
+    c = 0
+    while c < 3 and n > 1
+	if (n mod a) = 0 then
+	    n = n / a
+	    c = c + 1
+        else
+	    a = a + 1
+        end if
+    end while
+	if c = 2 then return "True"
+	return "False"
+end function
+
+for i = 0 to 64
+    print i, semiprime$(i)
+next i
+end

Task/Semiprime/Bracmat/semiprime-1.bracmat

@@ -0,0 +1,7 @@
+semiprime=
+  m n a b
+.   2^-64:?m
+  & 2*!m:?n
+  &   !arg^!m
+    : (#%?a^!m*#%?b^!m|#%?a^!n&!a:?b)
+  & (!a.!b);

Task/Semiprime/Bracmat/semiprime-2.bracmat

@@ -0,0 +1,7 @@
+  2^63:?u
+&   whl
+  ' ( -1+!u:>2:?u
+    & ( semiprime$!u:?R&out$(!u ":" !R)
+      |
+      )
+    );

Task/Semiprime/C++/semiprime.cpp

@@ -0,0 +1,21 @@
+#include <iostream>
+
+bool isSemiPrime( int c )
+{
+    int a = 2, b = 0;
+    while( b < 3 && c != 1 )
+    {
+	if( !( c % a ) )
+	{ c /= a; b++; }
+	else a++;
+    }
+    return b == 2;
+}
+int main( int argc, char* argv[] )
+{
+    for( int x = 2; x < 100; x++ )
+	if( isSemiPrime( x ) )
+	    std::cout << x << " ";
+
+    return 0;
+}

Task/Semiprime/C-sharp/semiprime.cs

@@ -0,0 +1,28 @@
+static void Main(string[] args)
+{
+    //test some numbers
+    for (int i = 0; i < 50; i++)
+    {
+        Console.WriteLine("{0}\t{1} ", i,isSemiPrime(i));
+    }
+    Console.ReadLine();
+}
+
+//returns true or false depending if input was considered semiprime
+private static bool isSemiPrime(int c)
+{
+    int a = 2, b = 0;
+    while (b < 3 && c != 1)
+    {
+        if ((c % a) == 0)
+        {
+            c /= a;
+            b++;
+        }
+        else
+        {
+            a++;
+        };
+    }
+    return b == 2;
+}

Task/Semiprime/C/semiprime.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+
+int semiprime(int n)
+{
+	int p, f = 0;
+	for (p = 2; f < 2 && p*p <= n; p++)
+		while (0 == n % p)
+			n /= p, f++;
+
+	return f + (n > 1) == 2;
+}
+
+int main(void)
+{
+	int i;
+	for (i = 2; i < 100; i++)
+		if (semiprime(i)) printf(" %d", i);
+	putchar('\n');
+
+	return 0;
+}

Task/Semiprime/Chipmunk-Basic/semiprime.basic

@@ -0,0 +1,14 @@
+100 rem Semiprime
+110 cls
+120 for i = 0 to 64
+130   print using "##  ";i semiprime$(i)
+140 next i
+150 end
+160 sub semiprime$(n)
+170 a = 2
+180 c = 0
+190 do while c < 3 and n > 1
+200   if n mod a = 0 then n = n/a : c = c+1 else a = a+1
+210 loop
+220 if c = 2 then semiprime$ = "True" else semiprime$ = "False"
+230 end sub

Task/Semiprime/Clojure/semiprime.clj

@@ -0,0 +1,14 @@
+(ns example
+  (:gen-class))
+
+(defn semi-prime? [n]
+  (loop [a 2
+         b 0
+         c n]
+    (cond
+      (> b 2) false
+      (<= c 1) (= b 2)
+      (= 0 (rem c a)) (recur a (inc b) (int (/ c a)))
+      :else (recur (inc a) b c))))
+
+(println (filter semi-prime? (range 1 100)))

Task/Semiprime/Common-Lisp/semiprime.lisp

@@ -0,0 +1,9 @@
+(defun semiprimep (n &optional (a 2))
+  (cond ((> a (isqrt n)) nil)
+        ((zerop (rem n a)) (and (primep a) (primep (/ n a))))
+        (t (semiprimep n (+ a 1)))))
+
+(defun primep (n &optional (a 2))
+  (cond ((> a (isqrt n)) t)
+        ((zerop (rem n a)) nil)
+        (t (primep n (+ a 1)))))

Task/Semiprime/Crystal/semiprime-1.crystal

@@ -0,0 +1,13 @@
+def semiprime(n)
+  nf = 0
+  (2..n).each do |i|
+    while n % i == 0
+      return false if nf == 2
+      nf += 1
+      n  /= i
+    end
+  end
+  nf == 2
+end
+
+(1675..1681).each { |n| puts "#{n} -> #{semiprime(n)}" }

Task/Semiprime/Crystal/semiprime-2.crystal

@@ -0,0 +1,5 @@
+def semiprime(n)
+  `factor #{n}`.split(' ').size == 3
+end
+n = 0xffffffffffffffff_u64 # 2**64 - 1 = 18446744073709551615
+(n-50..n).each { |n| puts "#{n} -> #{semiprime(n)}" }

Task/Semiprime/D/semiprime.d

@@ -0,0 +1,19 @@
+bool semiprime(long n) pure nothrow @safe @nogc {
+    auto nf = 0;
+    foreach (immutable i; 2 .. n + 1) {
+        while (n % i == 0) {
+            if (nf == 2)
+                return false;
+            nf++;
+            n /= i;
+        }
+    }
+    return nf == 2;
+}
+
+void main() {
+    import std.stdio;
+
+    foreach (immutable n; 1675 .. 1681)
+        writeln(n, " -> ", n.semiprime);
+}

Task/Semiprime/DCL/semiprime.dcl

@@ -0,0 +1,48 @@
+$ p1 = f$integer( p1 )
+$ if p1 .lt. 2
+$ then
+$  write sys$output "out of range 2 thru 2^31-1"
+$  exit
+$ endif
+$
+$ close /nolog primes
+$ on control_y then $ goto clean
+$ open primes primes.txt
+$
+$ loop1:
+$  read /end_of_file = prime primes prime
+$  prime = f$integer( prime )
+$  loop2:
+$   t = p1 / prime
+$   if t * prime .eq. p1
+$   then
+$    if f$type( factorization ) .eqs. ""
+$    then
+$     factorization = f$string( prime )
+$    else
+$     factorization = factorization + "*" + f$string( prime )
+$    endif
+$    if t .eq. 1 then $ goto done
+$    p1 = t
+$    goto loop2
+$   else
+$    goto loop1
+$   endif
+$ prime:
+$ if f$type( factorization ) .eqs. ""
+$ then
+$  factorization = f$string( p1 )
+$ else
+$  factorization = factorization + "*" + f$string( p1 )
+$ endif
+$ done:
+$ show symbol factorization
+$ if f$locate( "*", factorization ) .eq. f$length( factorization )
+$ then
+$  write sys$output "so, it is prime"
+$ else
+$  if f$element( 2, "*", factorization ) .eqs. "*" then $ write sys$output "so, it is semiprime"
+$ endif
+$
+$ clean:
+$ close primes

Task/Semiprime/Delphi/semiprime.delphi

@@ -0,0 +1,48 @@
+{This function would normally be in a library, but it shown here for clarity}
+
+procedure GetAllFactors(N: Integer;var IA: TIntegerDynArray);
+{Make a list of all irreducible factor of N}
+var I: integer;
+begin
+SetLength(IA,1);
+IA[0]:=1;
+for I:=2 to N do
+ while (N mod I)=0 do
+	begin
+	SetLength(IA,Length(IA)+1);
+	IA[High(IA)]:=I;
+	N:=N div I;
+	end;
+end;
+
+
+function IsSemiprime(N: integer): boolean;
+{Test if number is semiprime}
+var IA: TIntegerDynArray;
+begin
+{Get all factors of N}
+GetAllFactors(N,IA);
+Result:=False;
+{Since 1 is factor, ignore it}
+if Length(IA)<>3 then exit;
+Result:=IsPrime(IA[1]) and IsPrime(IA[2]);
+end;
+
+
+procedure Semiprimes(Memo: TMemo);
+var I,Cnt: integer;
+var S: string;
+begin
+Cnt:=0;
+S:='';
+{Test first 100 number to see if they are semiprime}
+for I:=0 to 100-1 do
+ if IsSemiprime(I) then
+	begin
+	Inc(Cnt);
+	S:=S+Format('%4d',[I]);
+	if (Cnt mod 10)= 0 then S:=S+CRLF;
+	end;
+Memo.Lines.Add(S);
+Memo.Lines.Add('Count='+IntToStr(Cnt));
+end;

Task/Semiprime/ERRE/semiprime.erre

@@ -0,0 +1,26 @@
+PROGRAM SEMIPRIME_NUMBER
+
+!VAR I%
+
+PROCEDURE SEMIPRIME(N%->RESULT%)
+   LOCAL F%,P%
+   P%=2
+   LOOP
+       EXIT IF NOT(F%<2 AND P%*P%<=N%)
+       WHILE (N% MOD P%)=0 DO
+            N%=N% DIV P%
+            F%+=1
+       END WHILE
+       P%+=1
+    END LOOP
+    RESULT%=F%-(N%>1)=2
+END PROCEDURE
+
+BEGIN
+    PRINT(CHR$(12);) !CLS
+    FOR I%=2 TO 100 DO
+         SEMIPRIME(I%->RESULT%)
+         IF RESULT% THEN PRINT(I%;) END IF
+    END FOR
+    PRINT
+END PROGRAM

Task/Semiprime/EchoLisp/semiprime.l

@@ -0,0 +1,20 @@
+(lib 'math)
+(define (semi-prime? n)
+   (= (length (prime-factors n)) 2))
+
+(for ((i 100))
+    (when (semi-prime? i) (write i)))
+
+4 6 9 10 14 15 21 22 25 26 33 34 35 38 39 46 49 51 55 57 58 62 65 69 74 77 82 85 86 87 91 93 94 95
+
+(lib 'bigint)
+(define N (* (random-prime 10000000) (random-prime 10000000)))
+   → 6764578882969
+(semi-prime? N)
+    → #t
+
+;; a pair n,n+1 of semi-primes
+(prime-factors 100000000041)
+    → (3 33333333347)
+(prime-factors 100000000042)
+    → (2 50000000021)

Task/Semiprime/Elixir/semiprime.elixir

@@ -0,0 +1,14 @@
+defmodule Prime do
+  def semiprime?(n), do: length(decomposition(n)) == 2
+
+  def decomposition(n), do: decomposition(n, 2, [])
+
+  defp decomposition(n, k, acc) when n < k*k, do: Enum.reverse(acc, [n])
+  defp decomposition(n, k, acc) when rem(n, k) == 0, do: decomposition(div(n, k), k, [k | acc])
+  defp decomposition(n, k, acc), do: decomposition(n, k+1, acc)
+end
+
+IO.inspect Enum.filter(1..100, &Prime.semiprime?(&1))
+Enum.each(1675..1680, fn n ->
+  :io.format "~w -> ~w\t~s~n", [n, Prime.semiprime?(n), Prime.decomposition(n)|>Enum.join(" x ")]
+end)

Task/Semiprime/Erlang/semiprime.erl

@@ -0,0 +1,19 @@
+-module(factors).
+-export([factors/1,kthfactor/2]).
+
+factors(N) ->
+     factors(N,2,[]).
+
+factors(1,_,Acc) -> Acc;
+factors(N,K,Acc) when N rem K == 0 ->
+    factors(N div K,K, [K|Acc]);
+factors(N,K,Acc) ->
+    factors(N,K+1,Acc).
+
+
+% is integer N factorable into M primes?
+kthfactor(N,M) ->
+    case length(factors(N)) of M ->
+      factors(N);
+      _ ->
+      false end.

Task/Semiprime/F-Sharp/semiprime.fs

@@ -0,0 +1,15 @@
+let isSemiprime (n: int) =
+    let rec loop currentN candidateFactor numberOfFactors =
+        if numberOfFactors > 2 then numberOfFactors
+        elif currentN = candidateFactor then numberOfFactors+1
+        elif currentN % candidateFactor = 0 then loop (currentN/candidateFactor) candidateFactor (numberOfFactors+1)
+        else loop currentN (candidateFactor+1) numberOfFactors
+    if n < 2 then false else 2 = loop n 2 0
+
+seq { 1 .. 100 } |> Seq.choose (fun n -> if isSemiprime n then Some(n) else None)
+|> Seq.toList |> printfn "%A"
+
+seq { 1675 .. 1680 }
+|> Seq.choose (fun n -> if isSemiprime n then Some(n) else None)
+|> Seq.toList
+|> printfn "%A"

Task/Semiprime/Factor/semiprime-1.factor

@@ -0,0 +1,3 @@
+USING: io kernel math.primes.factors prettyprint sequences ;
+
+: semiprime? ( n -- ? ) factors length 2 = ;

Task/Semiprime/Factor/semiprime-2.factor

@@ -0,0 +1 @@
+100 <iota> [ semiprime? ] filter [ bl ] [ pprint ] interleave nl

Task/Semiprime/Forth/semiprime.fth

@@ -0,0 +1,8 @@
+: semiprime?
+  0 swap dup 2 do
+    begin dup i mod 0= while i / swap 1+ swap repeat
+    over 1 > over i dup * < or if leave then
+  loop 1 > abs + 2 =
+;
+
+: test 100 2 do i semiprime? if i . then loop cr ;

Task/Semiprime/FreeBASIC/semiprime.basic

@@ -0,0 +1,17 @@
+function semiprime( n as uinteger ) as boolean
+	dim as uinteger a = 2, c = 0
+	while c < 3 andalso n > 1
+		if n mod a = 0 then
+			n /= a
+			c += 1
+		else
+			a += 1
+		end if
+	wend
+	if c = 2 then return true
+	return false
+end function
+
+for i as uinteger = 0 to 64
+    print i, semiprime(i)
+next i

Task/Semiprime/Frink/semiprime.frink

@@ -0,0 +1 @@
+isSemiprime[n] := length[factorFlat[n]] == 2

Task/Semiprime/GW-BASIC/semiprime.basic

@@ -0,0 +1,8 @@
+10 INPUT "Enter a number: ", N
+20 N=ABS(N)
+30 C = 0
+40 IF N < 3 THEN GOTO 80
+50 F = 2
+60 IF N MOD F = 0 THEN C = C + 1 : N = N / F ELSE F = F + 1
+70 IF N > 1 THEN GOTO 60
+80 IF C=2 THEN PRINT "It's a semiprime." ELSE PRINT "It is not a semiprime."

Task/Semiprime/Go/semiprime.go

@@ -0,0 +1,23 @@
+package main
+
+import "fmt"
+
+func semiprime(n int) bool {
+    nf := 0
+    for i := 2; i <= n; i++ {
+        for n%i == 0 {
+            if nf == 2 {
+                return false
+            }
+            nf++
+            n /= i
+        }
+    }
+    return nf == 2
+}
+
+func main() {
+    for v := 1675; v <= 1680; v++ {
+        fmt.Println(v, "->", semiprime(v))
+    }
+}

Task/Semiprime/Haskell/semiprime-1.hs

@@ -0,0 +1,4 @@
+isSemiprime :: Int -> Bool
+isSemiprime n = (length factors) == 2 && (product factors) == n ||
+                (length factors) == 1 && (head factors) ^ 2 == n
+                    where factors = primeFactors n

Task/Semiprime/Haskell/semiprime-2.hs

@@ -0,0 +1,4 @@
+isSemiprime :: Int -> Bool
+isSemiprime n = case (primeFactors n) of
+                   [f1, f2] -> f1 * f2 == n
+                   otherwise -> False

Task/Semiprime/Icon/semiprime.icon

@@ -0,0 +1,9 @@
+link "factors"
+
+procedure main(A)
+    every nf := semiprime(n := !A) do write(n," = ",nf[1]," * ",nf[2])
+end
+
+procedure semiprime(n)  # Succeeds and produces the factors only if n is semiprime.
+    return (2 = *(nf := factors(n)), nf)
+end

Task/Semiprime/J/semiprime-1.j

@@ -0,0 +1 @@
+isSemiPrime=: 2 = #@q: ::0:"0

Task/Semiprime/J/semiprime-2.j

@@ -0,0 +1,2 @@
+   I. isSemiPrime i.100
+4 6 9 10 14 15 21 22 25 26 33 34 35 38 39 46 49 51 55 57 58 62 65 69 74 77 82 85 86 87 91 93 94 95

Task/Semiprime/Java/semiprime.java

@@ -0,0 +1,57 @@
+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.List;
+
+public class SemiPrime{
+	private static final BigInteger TWO = BigInteger.valueOf(2);
+	
+	public static List<BigInteger> primeDecomp(BigInteger a){
+	    // impossible for values lower than 2
+	    if(a.compareTo(TWO) < 0){
+	        return null;
+	    }
+	
+	    //quickly handle even values
+	    List<BigInteger> result = new ArrayList<BigInteger>();
+	    while(a.and(BigInteger.ONE).equals(BigInteger.ZERO)){
+	        a = a.shiftRight(1);
+	        result.add(TWO);
+	    }
+	
+	    //left with odd values
+	    if(!a.equals(BigInteger.ONE)){
+	        BigInteger b = BigInteger.valueOf(3);
+	        while(b.compareTo(a) < 0){
+	            if(b.isProbablePrime(10)){
+	                BigInteger[] dr = a.divideAndRemainder(b);
+	                if(dr[1].equals(BigInteger.ZERO)){
+	                    result.add(b);
+	                    a = dr[0];
+	                }
+	            }
+	            b = b.add(TWO);
+	        }
+	        result.add(b); //b will always be prime here...
+	    }
+	    return result;
+	}
+	
+	public static boolean isSemi(BigInteger x){
+		List<BigInteger> decomp = primeDecomp(x);
+		return decomp != null && decomp.size() == 2;
+	}
+	
+	public static void main(String[] args){
+		for(int i = 2; i <= 100; i++){
+			if(isSemi(BigInteger.valueOf(i))){
+				System.out.print(i + " ");
+			}
+		}
+		System.out.println();
+		for(int i = 1675; i <= 1680; i++){
+			if(isSemi(BigInteger.valueOf(i))){
+				System.out.print(i + " ");
+			}
+		}
+	}
+}

Task/Semiprime/Jq/semiprime-1.jq

@@ -0,0 +1,10 @@
+def is_semiprime:
+  {i: 2, n: ., nf: 0}
+  | until( .i > .n or .result;
+      until(.n % .i != 0 or .result;
+        if .nf == 2 then .result = 0
+        else .nf += 1
+        | .n /= .i
+        end)
+      | .i += 1)
+  | if .result == 0 then false else .nf == 2 end;

Task/Semiprime/Jq/semiprime-2.jq

@@ -0,0 +1 @@
+(1679, 1680) | "\(.) => \(is_semiprime)"

Task/Semiprime/Julia/semiprime.julia

@@ -0,0 +1,3 @@
+using Primes
+issemiprime(n::Integer) = sum(values(factor(n))) == 2
+@show filter(issemiprime, 1:100)

Task/Semiprime/Kotlin/semiprime.kotlin

@@ -0,0 +1,18 @@
+// version 1.1.2
+
+fun isSemiPrime(n: Int): Boolean {
+    var nf = 0
+    var nn = n
+    for (i in 2..nn)
+        while (nn % i == 0) {
+            if (nf == 2) return false
+            nf++
+            nn /= i
+        }
+    return nf == 2
+}
+
+fun main(args: Array<String>) {
+    for (v in 1675..1680)
+        println("$v ${if (isSemiPrime(v)) "is" else "isn't"} semi-prime")
+}

Task/Semiprime/Ksh/semiprime.ksh

@@ -0,0 +1,35 @@
+#!/bin/ksh
+
+# Semiprime - As translated from C
+
+#	# Variables:
+#
+
+#	# Functions:
+#
+# Function _issemiprime(p2) - return 1 if p2 semiprime, 0 if not
+#
+function _issemiprime {
+	typeset _p2 ; integer _p2=$1
+	typeset _p _f ; integer _p _f=0
+
+	for ((_p=2; (_f<2 && _p*_p<=_p2); _p++)); do
+		while (( _p2 % _p == 0 )); do
+			(( _p2 /= _p ))
+			(( _f++ ))
+		done
+	done
+
+	return $(( _f + (_p2 > 1) == 2 ))
+}
+
+ ######
+# main #
+ ######
+
+integer i
+for ((i=2; i<100; i++)); do
+	_issemiprime ${i}
+	(( $? )) && printf " %d" ${i}
+done
+echo

Task/Semiprime/Lambdatalk/semiprime.lambdatalk

@@ -0,0 +1,65 @@
+{def factors
+ {def factors.r
+  {lambda {:n :i}
+   {if {> :i :n}
+    then
+    else {if {= {% :n :i} 0}
+    then :i {factors.r {/ :n :i} :i}
+    else {factors.r :n {+ :i 1}} }}}}
+ {lambda {:n}
+   {A.new {factors.r :n 2} }}}
+-> factors
+
+{factors 491} -> [491]        // prime
+{factors 492} -> [2,2,3,41]
+{factors 493} -> [17,29]      // semiprime
+{factors 494} -> [2,13,19]
+{factors 495} -> [3,3,5,11]
+{factors 496} -> [2,2,2,2,31]
+{factors 497} -> [7,71]       // semiprime
+{factors 498} -> [2,3,83]
+{factors 499} -> [499]        // prime
+{factors 500} -> [2,2,5,5,5]
+
+{S.replace \s by space in
+ {S.map {lambda {:i}
+         {let { {:i :i} {:f {factors :i}}
+              } {if {= {A.length :f} 2}
+                 then :i={A.first :f}*{A.last :f}
+                 else}} }
+       {S.serie 1 100}}}
+->
+4 = 2*2
+6 = 2*3
+9 = 3*3
+10 = 2*5
+14 = 2*7
+15 = 3*5
+21 = 3*7
+22 = 2*11
+25 = 5*5
+26 = 2*13
+33 = 3*11
+34 = 2*17
+35 = 5*7
+38 = 2*19
+39 = 3*13
+46 = 2*23
+49 = 7*7
+51 = 3*17
+55 = 5*11
+57 = 3*19
+58 = 2*29
+62 = 2*31
+65 = 5*13
+69 = 3*23
+74 = 2*37
+77 = 7*11
+82 = 2*41
+85 = 5*17
+86 = 2*43
+87 = 3*29
+91 = 7*13
+93 = 3*31
+94 = 2*47
+95 = 5*19

Task/Semiprime/Lingo/semiprime-1.lingo

@@ -0,0 +1,13 @@
+on isSemiPrime (n)
+    div = 2
+    cnt = 0
+    repeat while cnt < 3 and n <> 1
+        if n mod div = 0 then
+            n = n / div
+            cnt = cnt + 1
+        else
+            div = div + 1
+        end if
+    end repeat
+    return cnt=2
+end

Task/Semiprime/Lingo/semiprime-2.lingo

@@ -0,0 +1,5 @@
+res = []
+repeat with i = 1 to 100
+    if isSemiPrime(i) then res.add(i)
+end repeat
+put res

Task/Semiprime/Lua/semiprime.lua

@@ -0,0 +1,16 @@
+function semiprime (n)
+	local divisor, count = 2, 0
+	while count < 3 and n ~= 1 do
+		if n % divisor == 0 then
+			n = n / divisor
+			count = count + 1
+		else
+			divisor = divisor + 1
+		end
+	end
+	return count == 2
+end
+
+for n = 1675, 1680 do
+	print(n, semiprime(n))
+end

Task/Semiprime/Maple/semiprime-1.maple

@@ -0,0 +1,10 @@
+SemiPrimes := proc( n )
+    local fact;
+    fact := NumberTheory:-Divisors( n ) minus {1, n};
+    if numelems( fact ) in {1,2} and not( member( 'false', isprime ~ ( fact ) ) ) then
+        return n;
+    else
+        return NULL;
+    end if;
+end proc:
+{ seq( SemiPrimes( i ), i = 1..100 ) };

Task/Semiprime/Maple/semiprime-2.maple

@@ -0,0 +1 @@
+{ 4,6,9,10,14,15,21,22,25,26,33,34,35,38,39,46,49,51,55,57,58,62,65,69,74,77,82,85,86,87,91,93,94,95 }

Task/Semiprime/Mathematica/semiprime-1.math

@@ -0,0 +1,5 @@
+semiPrimeQ[n_Integer] := Module[{factors, numfactors},
+  factors = FactorInteger[n] // Transpose;
+  numfactors = factors[[2]] // Total  ;
+  numfactors == 2
+  ]

Task/Semiprime/Mathematica/semiprime-2.math

@@ -0,0 +1,2 @@
+semiPrimeQ[#] & /@ Range[100];
+Position[%, True] // Flatten

Task/Semiprime/MiniScript/semiprime.mini

@@ -0,0 +1,20 @@
+isSemiprime = function(num)
+    divisor = 2
+    primes = 0
+    while primes < 3 and num != 1
+        if num % divisor == 0 then
+            num = num / divisor;
+            primes = primes + 1
+        else
+            divisor = divisor + 1
+        end if
+    end while
+    return primes == 2
+end function
+
+print "Semiprimes up to 100:"
+results = []
+for i in range(2, 100)
+    if isSemiprime(i) then results.push i
+end for
+print results

Task/Semiprime/Minimal-BASIC/semiprime.basic

@@ -0,0 +1,17 @@
+10 REM Semiprime
+20 PRINT "Enter an integer";
+30 INPUT N
+40 LET N = ABS(N)
+50 LET C = 0
+60 IF N < 2 THEN 130
+70 FOR F = 2 TO N
+80 IF INT(N/F)*F <> N THEN 120
+90 LET C = C+1
+100 LET N = N/F
+110 GOTO 80
+120 NEXT F
+130 IF C <> 2 THEN 160
+140 PRINT "It is a semiprime."
+150 GOTO 170
+160 PRINT "It is not a semiprime."
+170 END

Task/Semiprime/NewLISP/semiprime.l

@@ -0,0 +1,9 @@
+;;;	Practically identical to the EchoLisp solution
+(define (semiprime? n)
+	(= (length (factor n)) 2))
+;
+;;;	Example (sadly factor doesn't accept bigints)
+(println (filter semiprime? (sequence 2 100)))
+(setq x 9223372036854775807)
+(while (not (semiprime? x)) (-- x))
+(println "Biggest semiprime reachable: " x " = " ((factor x) 0) " x " ((factor x) 1))

Task/Semiprime/Nim/semiprime.nim

@@ -0,0 +1,15 @@
+proc isSemiPrime(k: int): bool =
+ var
+  i = 2
+  count = 0
+  x = k
+ while i <= x and count < 3:
+  if x mod i == 0:
+   x = x div i
+   inc count
+  else:
+   inc i
+ result = count == 2
+
+for k in 1675..1680:
+ echo k, (if k.isSemiPrime(): " is" else: " isn’t"), " semi-prime"

Task/Semiprime/Objeck/semiprime.objeck

@@ -0,0 +1,25 @@
+class SemiPrime {
+  function : Main(args : String[]) ~ Nil {
+    for(i := 0; i < 100; i+=1;) {
+      if(SemiPrime(i)) {
+        "{$i} "->Print();
+      };
+    };
+    IO.Console->PrintLine();
+  }
+
+  function : native : SemiPrime(n : Int) ~ Bool {
+    nf := 0;
+    for(i := 2; i <= n; i+=1;) {
+      while(n%i = 0) {
+        if(nf = 2) {
+          return false;
+        };
+        nf+=1;
+        n /= i;
+      };
+    };
+
+    return nf = 2;
+  }
+}

Task/Semiprime/Oforth/semiprime.fth

@@ -0,0 +1,4 @@
+func: semiprime(n)
+| i |
+   0 2 n sqrt asInteger for: i [ while(n i /mod swap 0 &=) [ ->n 1+ ] drop ]
+   n 1 > ifTrue: [ 1+ ] 2 == ;

Task/Semiprime/PARI-GP/semiprime-1.parigp

@@ -0,0 +1 @@
+issemi(n)=bigomega(n)==2

Task/Semiprime/PARI-GP/semiprime-2.parigp

@@ -0,0 +1,5 @@
+issemi(n)={
+  forprime(p=2,97,if(n%p==0, return(isprime(n/p))));
+  if(isprime(n), return(0));
+  bigomega(n)==2
+};

Task/Semiprime/PARI-GP/semiprime-3.parigp

@@ -0,0 +1,77 @@
+long
+issemiprime(GEN n)
+{
+  if (typ(n) != t_INT)
+    pari_err_TYPE("issemiprime", n);
+  if (signe(n) <= 0)
+    return 0;
+
+  ulong nn = itou_or_0(n);
+  if (nn)
+    return uissemiprime(nn);
+
+  pari_sp ltop = avma;
+  if (!mpodd(n)) {
+    long ret = mod4(n) && isprime(shifti(n, -1));
+    avma = ltop;
+    return ret;
+  }
+
+
+  long p;
+  forprime_t primepointer;
+  u_forprime_init(&primepointer, 3, 997);
+  while ((p = u_forprime_next(&primepointer))) {
+    if (dvdis(n, p)) {
+      long ret = isprime(diviuexact(n, p));
+      avma = ltop;
+      return ret;
+    }
+  }
+
+  if (isprime(n))
+    return 0;
+
+  if (DEBUGLEVEL > 3)
+    pari_printf("issemi: Number is a composite with no small prime factors; using general factoring mechanisms.");
+
+  GEN fac = Z_factor_until(n, shifti(n, -1));	/* Find a nontrivial factor -- returns just the factored part */
+  GEN expo = gel(fac, 2);
+  GEN pr = gel(fac, 1);
+  long len = glength(expo);
+  if (len > 2) {
+    avma = ltop;
+    return 0;
+  }
+  if (len == 2) {
+    if (cmpis(gel(expo, 1), 1) > 0 || cmpis(gel(expo, 2), 1) > 0) {
+      avma = ltop;
+      return 0;
+    }
+    GEN P = gel(pr, 1);
+    GEN Q = gel(pr, 2);
+    long ret = isprime(P) && isprime(Q) && equalii(mulii(P, Q), n);
+    avma = ltop;
+    return ret;
+  }
+  if (len == 1) {
+    long e = itos(gel(expo, 1));
+    if (e == 2) {
+      GEN P = gel(pr, 1);
+      long ret = isprime(P) && equalii(sqri(P), n);
+      avma = ltop;
+      return ret;
+    } else if (e > 2) {
+      avma = ltop;
+      return 0;
+    }
+    GEN P = gel(pr, 1);
+    long ret = isprime(P) && isprime(diviiexact(n, P));
+    avma = ltop;
+    return ret;
+  }
+
+  pari_err_BUG(pari_sprintf("Z_factor_until returned an unexpected value %Ps at n = %Ps, exiting...", fac, n));
+  avma = ltop;
+  return 0; /* never used */
+}

Task/Semiprime/PHP/semiprime.php

@@ -0,0 +1,21 @@
+<?php
+// Semiprime
+
+function primeFactorsCount($n)
+{
+    $n = abs($n);
+    $count = 0; // Result
+    if ($n >= 2)
+        for ($factor = 2; $factor <= $n; $factor++)
+            while ($n % $factor == 0) {
+                $count++;
+                $n /= $factor;
+            }
+    return $count;
+}
+
+echo "Enter an integer: ",
+$n = (int)fgets(STDIN);
+echo (primeFactorsCount($n) == 2 ?
+      "It is a semiprime.\n" : "It is not a semiprime.\n");
+?>

Task/Semiprime/PL-0/semiprime.pl0

@@ -0,0 +1,20 @@
+var n, count, factor;
+begin
+  ? n;
+  if n < 0 then n := -n;
+  count := 0;
+  if n >= 2 then
+  begin
+    factor := 2;
+    while factor <= n do
+    begin
+      while (n / factor) * factor = n do
+      begin
+        count := count + 1; n := n / factor
+      end;
+      factor := factor + 1
+    end;
+  end;
+  if count = 2 then ! 1;
+  if count <> 2 then ! 0
+end.

Task/Semiprime/PL-I/semiprime.pli

@@ -0,0 +1,89 @@
+*process source attributes xref nest or(!);
+ /*--------------------------------------------------------------------
+ * 22.02.2014 Walter Pachl using the is_prime code from
+ *                         PL/I 'prime decomposition'
+ * 23.02.  WP start test for second prime with 2 or first prime found
+ *-------------------------------------------------------------------*/
+ spb: Proc options(main);
+ Dcl a(10) Bin Fixed(31)
+          Init(900660121,2,4,1679,1234567,32768,99,9876543,100,5040);
+ Dcl (x,n,nf,i,j) Bin Fixed(31) Init(0);
+ Dcl f(3) Bin Fixed(31);
+ Dcl txt Char(30) Var;
+ Dcl bit Bit(1);
+ Do i=1 To hbound(a);
+   bit=is_semiprime(a(i));
+   Select(nf);
+     When(0,1) txt=' is prime';
+     When(2)   txt=' is     semiprime '!!factors(a(i));
+     Otherwise txt=' is NOT semiprime '!!factors(a(i));
+     End;
+   Put Edit(a(i),bit,txt)(Skip,f(10),x(1),b(1),a);
+   End;
+
+ is_semiprime: Proc(x) Returns(bit(1));
+ /*--------------------------------------------------------------------
+ * Returns '1'b if x is semiprime, '0'b otherwise
+ * in addition
+ * it sets f(1) and f(2) to the first (or only) prime factor(s)
+ *-------------------------------------------------------------------*/
+   Dcl x Bin Fixed(31);
+   nf=0;
+   f=0;
+   x=a(i);
+   n=x;
+   f(1)=2;
+ loop:
+   Do While(nf<=2 & n>1);
+     If is_prime(n) Then Do;
+       Call mem(n);
+       Leave loop;
+       End;
+     Else Do;
+ loop2:
+       Do j=f(1) By 1 While(j*j<=n);
+         If is_prime(j)&mod(n,j)=0 Then Do;
+           Call mem(j);
+           n=n/j;
+           Leave loop2;
+           End;
+         End;
+       End;
+     End;
+   Return(nf=2);
+ End;
+
+ is_prime: Proc(n) Returns(bit(1));
+ Dcl n Bin Fixed(31);
+ Dcl i Bin Fixed(31);
+   If n < 2 Then Return('0'b);
+   If n = 2 Then Return('1'b);
+   If mod(n,2)=0 Then Return('0'b);
+   Do i = 3 by 2 While(i*i<=n);
+     If mod(n,i)=0 Then Return('0'b);
+     End;
+   Return('1'b);
+ End is_prime;
+
+ mem: Proc(x);
+ Dcl x Bin Fixed(31);
+   nf+=1;
+   f(nf)=x;
+ End;
+
+ factors: Proc(x) Returns(Char(150) Var);
+ Dcl x Bin Fixed(31);
+ Dcl (res,net) Char(150) Var Init('');
+ Dcl (i,f3) Bin Fixed(31);
+ res=f(1)!!'*'!!f(2);
+ f3=x/(f(1)*f(2));
+ If f3>1 Then
+   res=res!!'*'!!f3;
+ Do i=1 To length(res);
+   If substr(res,i,1)>' ' Then
+     net=net!!substr(res,i,1);
+   End;
+ Return(net);
+ End;
+
+ End spb;

Task/Semiprime/PL-M/semiprime.plm

@@ -0,0 +1,46 @@
+100H: /* FIND SOME SEMI-PRIMES - NUMBERS WITH EXACTLY 2 PRIME FACTORS       */
+
+   /* CP/M BDOS SYSTEM CALL AND I/O ROUTINES                                */
+   BDOS: PROCEDURE( FN, ARG ); DECLARE FN BYTE, ARG ADDRESS; GOTO 5; END;
+   PR$CHAR:   PROCEDURE( C ); DECLARE C BYTE;    CALL BDOS( 2, C );  END;
+   PR$STRING: PROCEDURE( S ); DECLARE S ADDRESS; CALL BDOS( 9, S );  END;
+   PR$NL:     PROCEDURE;   CALL PR$CHAR( 0DH ); CALL PR$CHAR( 0AH ); END;
+   PR$NUMBER: PROCEDURE( N ); /* PRINTS A NUMBER IN THE MINIMUN FIELD WIDTH  */
+      DECLARE N ADDRESS;
+      DECLARE V ADDRESS, N$STR ( 6 )BYTE, W BYTE;
+      V = N;
+      W = LAST( N$STR );
+      N$STR( W ) = '$';
+      N$STR( W := W - 1 ) = '0' + ( V MOD 10 );
+      DO WHILE( ( V := V / 10 ) > 0 );
+         N$STR( W := W - 1 ) = '0' + ( V MOD 10 );
+      END;
+      CALL PR$STRING( .N$STR( W ) );
+   END PR$NUMBER;
+
+   /* TASK                                                                  */
+
+   /* RETURNS TRUE IF V IS SEMI-PRIME, FALSE OTHERWISE                      */
+   IS$SEMI$PRIME: PROCEDURE( V )BYTE;
+      DECLARE V           ADDRESS;
+      DECLARE ( A, B, C ) ADDRESS;
+      A = 2; B = 0; C = V;
+      DO WHILE B < 3 AND C > 1;
+         IF C MOD A = 0 THEN DO;
+            C = C / A;
+            B = B + 1;
+            END;
+         ELSE A = A + 1;
+      END;
+      RETURN B = 2;
+   END IS$SEMI$PRIME;
+
+   DECLARE X ADDRESS;
+   DO X = 2 TO 99;
+      IF IS$SEMI$PRIME( X ) THEN DO;
+         CALL PR$NUMBER( X );
+         CALL PR$CHAR( ' ' );
+      END;
+   END;
+
+EOF

Task/Semiprime/PROMAL/semiprime.promal

@@ -0,0 +1,36 @@
+;;; find some semiprimes - numbers with two prime factors
+
+PROGRAM semiPrimes
+INCLUDE library
+
+FUNC BYTE isSemiPrime
+ARG WORD n
+WORD f
+WORD factorCount
+BYTE result
+BEGIN
+f = 2
+factorCount = 0
+WHILE factorCount < 3 AND n > 1
+  WHILE n % f = 0
+    factorCount = factorCount + 1
+    n = n / f
+  f = f + 1
+IF factorCOunt = 2
+  result = 1
+ELSE
+  result = 0
+RETURN result
+END
+
+WORD n
+BEGIN
+OUTPUT "Semiprimes under 100:#C   "
+FOR n = 1 TO 99
+  IF isSemiPrime( n )
+    OUTPUT " #W", n
+OUTPUT "#CSemiprimes between 1670 and 1690:#C   "
+FOR n = 1670 TO 1690
+  IF isSemiPrime( n )
+    OUTPUT " #W", n
+END

Task/Semiprime/Palo-Alto-Tiny-BASIC/semiprime.basic

@@ -0,0 +1,10 @@
+    10 REM SEMIPRIME
+    20 INPUT "ENTER AN INTEGER"N
+    30 LET N=ABS(N)
+    40 LET C=0
+    50 IF N<2 GOTO 90
+    60 FOR F=2 TO N
+    70 IF (N/F)*F=N LET C=C+1,N=N/F;GOTO 70
+    80 NEXT F
+    90 IF C=2 PRINT "IT IS A SEMIPRIME.";STOP
+   100 PRINT "IT IS NOT A SEMIPRIME.";STOP

Task/Semiprime/Pascal/semiprime.pas

@@ -0,0 +1,41 @@
+program SemiPrime;
+{$IFDEF FPC}
+  {$Mode objfpc}// compiler switch to use result
+{$ELSE}
+  {$APPTYPE CONSOLE} // for Delphi
+{$ENDIF}
+uses
+  primTrial;
+
+function isSemiprime(n: longWord;doWrite:boolean): boolean;
+var
+  fac1 : LongWord;
+begin
+  //a simple isAlmostPrime(n,2) would do without output;
+  fac1 := SmallFactor(n);
+  IF fac1 < n then
+  Begin
+    n := n div fac1;
+    result := SmallFactor(n) = n;
+    if result AND doWrite then
+      write(fac1:10,'*',n:11)
+  end
+  else
+    result := false;
+end;
+var
+  i,k : longWord;
+BEGIN
+  For i := 2 to 97 do
+    IF isSemiPrime(i,false) then
+      write(i:3);
+  writeln;
+  //test for big numbers
+  k := 4000*1000*1000;
+  i := k-100;
+  repeat
+    IF isSemiPrime(i,true) then
+      writeln(' = ',i:10);
+    inc(i);
+  until i> k;
+END.

Task/Semiprime/Perl/semiprime-1.pl

@@ -0,0 +1,4 @@
+use ntheory "is_semiprime";
+for ([1..100], [1675..1681], [2,4,99,100,1679,5030,32768,1234567,9876543,900660121]) {
+  print join(" ",grep { is_semiprime($_) } @$_),"\n";
+}

Task/Semiprime/Perl/semiprime-2.pl

@@ -0,0 +1,2 @@
+use ntheory "factor";
+print join(" ", grep { scalar factor($_) == 2 } 1..100),"\n";

Task/Semiprime/Perl/semiprime-3.pl

@@ -0,0 +1,9 @@
+use ntheory qw/factor is_prime trial_factor/;
+sub issemi {
+  my $n = shift;
+  if ((my @p = trial_factor($n,500)) > 1) {
+    return 0 if @p > 2;
+    return !!is_prime($p[1]) if @p == 2;
+  }
+  2 == factor($n);
+}

Task/Semiprime/Phix/semiprime.phix

@@ -0,0 +1,6 @@
+-->
+ <span style="color: #008080;">function</span> <span style="color: #000000;">semiprime</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
+     <span style="color: #008080;">return</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">prime_factors</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #004600;">true</span><span style="color: #0000FF;">))==</span><span style="color: #000000;">2</span>
+ <span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
+ <span style="color: #7060A8;">pp</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">filter</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">tagset</span><span style="color: #0000FF;">(</span><span style="color: #000000;">100</span><span style="color: #0000FF;">)&</span><span style="color: #7060A8;">tagset</span><span style="color: #0000FF;">(</span><span style="color: #000000;">1680</span><span style="color: #0000FF;">,</span><span style="color: #000000;">1675</span><span style="color: #0000FF;">),</span><span style="color: #000000;">semiprime</span><span style="color: #0000FF;">),{</span><span style="color: #004600;">pp_IntCh</span><span style="color: #0000FF;">,</span><span style="color: #004600;">false</span><span style="color: #0000FF;">})</span>
+<!--

Task/Semiprime/PicoLisp/semiprime.l

@@ -0,0 +1,21 @@
+(de factor (N)
+   (make
+      (let
+         (D 2
+            L (1 2 2 . (4 2 4 2 4 6 2 6 .))
+            M (sqrt N) )
+         (while (>= M D)
+            (if (=0 (% N D))
+               (setq M
+                  (sqrt (setq N (/ N (link D)))) )
+               (inc 'D (pop 'L)) ) )
+         (link N) ) ) )
+
+(println
+   (filter
+      '((X)
+         (let L (factor X)
+            (and (cdr L) (not (cddr L))) ) )
+      (conc (range 1 100) (range 1675 1680)) ) )
+
+(bye)

Task/Semiprime/PowerShell/semiprime.psh

@@ -0,0 +1,26 @@
+function isPrime ($n) {
+    if ($n -le 1) {$false}
+    elseif (($n -eq 2) -or ($n -eq 3)) {$true}
+    else{
+        $m = [Math]::Floor([Math]::Sqrt($n))
+        (@(2..$m | where {($_ -lt $n)  -and ($n % $_ -eq 0) }).Count -eq 0)
+    }
+}
+function semiprime ($n) {
+    if($n -gt 3) {
+        $lim = [Math]::Floor($n/2)+1
+        $i = 2
+        while(($i -lt $lim) -and ($n%$i -ne 0)){ $i += 1}
+        if($i -eq $lim){@()}
+        elseif(-not (isPrime ($n/$i))){@()}
+        else{@($i,($n/$i))}
+    } else {@()}
+}
+$OFS = " x "
+"1679: $(semiprime 1679)"
+"87: $(semiprime   87)"
+"25: $(semiprime 25)"
+"12: $(semiprime   12)"
+"6: $(semiprime   6)"
+$OFS = " "
+"semiprime from 1 to 100: $(1..100 | where {semiprime $_})"

Task/Semiprime/Prolog/semiprime.pro

@@ -0,0 +1,26 @@
+factors(N, FList):-
+	factors(N, 2, 0, FList).
+
+factors(1, _, _Count, []).
+factors(_, _, Count, []):- Count > 1. % break on 2 factors reached
+factors(N, Start, Count, [Fac|FList]):-
+	N1 is floor(sqrt(N)),
+	between(Start, N1, Fac),
+	N mod Fac =:= 0,!,
+	N2 is N div Fac,
+	Count1 is Count + 1,
+	factors(N2, Fac, Count1, FList).
+factors(N, _, _, [N]):- N >= 2.
+
+semiPrimeList(Limit, List):-
+	findall(N, semiPrimes(2, Limit, N), List).
+
+semiPrimes(Start, Limit, N):-
+	between(Start, Limit, N),
+	factors(N, [F1, F2]),
+	N =:= F1 * F2.	% correct factors break
+
+do:- semiPrimeList(100, SemiPrimes),
+	writeln(SemiPrimes),
+	findall(N, semiPrimes(1675, 1685, N), SemiPrimes2),
+	writeln(SemiPrimes2).

Task/Semiprime/PureBasic/semiprime.basic

@@ -0,0 +1,25 @@
+Procedure.s semiprime(n.i)
+    a.i = 2
+    c.i = 0
+    While c < 3 And n > 1
+	If (n % a) = 0
+	    n / a
+	    c + 1
+        Else
+	    a + 1
+        EndIf
+    Wend
+    If c = 2
+        ProcedureReturn "True" ;#True
+    EndIf
+    ProcedureReturn "False" ;#False
+EndProcedure
+	
+OpenConsole()
+For i.i = 0 To 64
+  PrintN(Str(i) + #TAB$ + semiprime(i))
+Next i
+
+PrintN(#CRLF$ + "--- terminado, pulsa RETURN---"): Input()
+CloseConsole()
+End

Task/Semiprime/Python/semiprime-1.py

@@ -0,0 +1,8 @@
+from prime_decomposition import decompose
+
+def semiprime(n):
+    d = decompose(n)
+    try:
+        return next(d) * next(d) == n
+    except StopIteration:
+        return False

Task/Semiprime/Python/semiprime-2.py

@@ -0,0 +1,5 @@
+>>> semiprime(1679)
+True
+>>> [n for n in range(1,101) if semiprime(n)]
+[4, 6, 9, 10, 14, 15, 21, 22, 25, 26, 33, 34, 35, 38, 39, 46, 49, 51, 55, 57, 58, 62, 65, 69, 74, 77, 82, 85, 86, 87, 91, 93, 94, 95]
+>>>

Task/Semiprime/Quackery/semiprime.quackery

@@ -0,0 +1,4 @@
+  [ primefactors size 2 = ] is semiprime ( n --> b )
+
+  say "Semiprimes less than 100:" cr
+  100 times [ i^ semiprime if [ i^ echo sp ] ]

Task/Semiprime/REXX/semiprime-1.rexx

@@ -0,0 +1,56 @@
+/* REXX ---------------------------------------------------------------
+* 20.02.2014 Walter Pachl  relying on 'prime decomposition'
+* 21.02.2014 WP Clarification: I copied the algorithm created by
+*            Gerard Schildberger under the task referred to above
+* 21.02.2014 WP Make sure that factr is not called illegally
+*--------------------------------------------------------------------*/
+Call test 4
+Call test 9
+Call test 10
+Call test 12
+Call test 1679
+Exit
+
+test:
+Parse Arg z
+If is_semiprime(z) Then Say z 'is semiprime' fl
+                   Else Say z 'is NOT semiprime' fl
+Return
+
+is_semiprime:
+  Parse Arg z
+  If z<1 | datatype(z,'W')=0 Then Do
+    Say 'Argument ('z') must be a natural number (1, 2, 3, ...)'
+    fl=''
+    End
+  Else
+    fl=factr(z)
+  Return words(fl)=2
+
+/*----------------------------------FACTR subroutine-----------------*/
+factr: procedure; parse arg x 1 z,list /*sets X&Z to arg1, LIST=''.  */
+if x==1  then return ''             /*handle the special case of X=1.*/
+j=2;     call .factr                /*factor for the only even prime.*/
+j=3;     call .factr                /*factor for the 1st  odd  prime.*/
+j=5;     call .factr                /*factor for the 2nd  odd  prime.*/
+j=7;     call .factr                /*factor for the 3rd  odd  prime.*/
+j=11;    call .factr                /*factor for the 4th  odd  prime.*/
+j=13;    call .factr                /*factor for the 5th  odd  prime.*/
+j=17;    call .factr                /*factor for the 6th  odd  prime.*/
+                                    /* [?]   could be optimized more.*/
+                                    /* [?]   J in loop starts at 17+2*/
+     do y=0  by 2;     j=j+2+y//4   /*insure J isn't divisible by 3. */
+     if right(j,1)==5  then iterate /*fast check for divisible by 5. */
+     if j*j>z          then leave   /*are we higher than the v of Z ?*/
+     if j>Z            then leave   /*are we higher than value of Z ?*/
+     call .factr                    /*invoke .FACTR for some factors.*/
+     end   /*y*/                    /* [?]  only tests up to the v X.*/
+                                    /* [?]  LIST has a leading blank.*/
+if z==1  then return list           /*if residual=unity, don't append*/
+              return list z         /*return list,  append residual. */
+/*-------------------------------.FACTR internal subroutine----------*/
+.factr:  do  while z//j==0          /*keep dividing until we can't.  */
+         list=list j                /*add number to the list  (J).   */
+         z=z%j                      /*% (percent)  is integer divide.*/
+         end   /*while z··· */      /*  //   ?---remainder integer ÷.*/
+return                              /*finished, now return to invoker*/

Task/Semiprime/REXX/semiprime-2.rexx

@@ -0,0 +1,35 @@
+/*REXX program determines if any integer  (or a range of integers)  is/are  semiprime.  */
+parse arg bot top .                              /*obtain optional arguments from the CL*/
+if bot=='' | bot==","  then bot=random()         /*None given?   User wants us to guess.*/
+if top=='' | top==","  then top=bot              /*maybe define a range of numbers.     */
+tell=  top=>0 |  top==bot                        /*should results be shown to the term? */
+w=max(length(bot), length(top)) + 5              /*obtain the maximum width of numbers. */
+numeric digits max(9, w)                         /*ensure there're enough decimal digits*/
+#=0                                              /*initialize number of semiprimes found*/
+             do n=bot  to abs(top)               /*show results for a range of numbers. */
+             ?=isSemiPrime(n);      #=#+?        /*Is N a semiprime?; Maybe bump counter*/
+             if tell  then say right(n,w)  right(word("isn't" 'is', ?+1), 6)  'semiprime.'
+             end   /*n*/
+say
+if bot\==top  then say 'found '   #   " semiprimes."
+exit                                             /*stick a fork in it,  we're all done. */
+/*──────────────────────────────────────────────────────────────────────────────────────*/
+isPrime: procedure;  parse arg x;               if x<2  then return 0  /*number too low?*/
+         if wordpos(x, '2 3 5 7 11 13 17 19 23')\==0    then return 1  /*it's low prime.*/
+         if x//2==0  then return 0;     if x//3==0      then return 0  /*÷ by 2; ÷ by 3?*/
+           do j=5  by 6  until j*j>x;   if x//j==0      then return 0  /*not a prime.   */
+                                        if x//(j+2)==0  then return 0  /* "  "   "      */
+           end   /*j*/
+         return 1                                /*indicate that  X  is a prime number. */
+/*──────────────────────────────────────────────────────────────────────────────────────*/
+isSemiPrime: procedure;  parse arg x;          if x<4  then return 0
+
+                           do i=2  for 2;  if x//i==0  then if isPrime(x%i)  then return 1
+                                                                             else return 0
+                           end   /*i*/
+                                                                             /*    ___  */
+               do   j=5  by 6;         if j*j>x    then  return 0            /* > √ x  ?*/
+                 do k=j  by 2  for 2;  if x//k==0  then  if isPrime(x%k)  then return 1
+                                                                          else return 0
+                 end   /*k*/                     /* [↑]  see if 2nd factor is prime or ¬*/
+               end     /*j*/                     /* [↑]  J is never a multiple of three.*/

Task/Semiprime/REXX/semiprime-3.rexx

@@ -0,0 +1,41 @@
+/*REXX program determines if any integer  (or a range of integers)  is/are  semiprime.  */
+parse arg bot top .                              /*obtain optional arguments from the CL*/
+if bot=='' | bot==","  then bot=random()         /*None given?   User wants us to guess.*/
+if top=='' | top==","  then top=bot              /*maybe define a range of numbers.     */
+tell= bot=>0  &  top=>0                          /*should results be shown to the term? */
+w=max(length(bot), length(top))                  /*obtain the maximum width of numbers. */
+!.=;  !.2=1; !.3=1; !.5=1; !.7=1; !.11=1; !.13=1; !.17=1; !.19=1; !.23=1; !.29=1;  !.31=1
+numeric digits max(9, w)                         /*ensure there're enough decimal digits*/
+#=0                                              /*initialize number of semiprimes found*/
+             do n=abs(bot)  to abs(top)          /*show results for a range of numbers. */
+             ?=isSemiPrime(n);      #=#+?        /*Is N a semiprime?; Maybe bump counter*/
+             if tell  then say right(n,w)  right(word("isn't" 'is', ?+1), 6)  'semiprime.'
+             end   /*n*/
+say
+if bot\==top  then say 'found '   #   " semiprimes."
+exit                                             /*stick a fork in it,  we're all done. */
+/*──────────────────────────────────────────────────────────────────────────────────────*/
+isPrime: procedure expose !.;  parse arg x;     if x<2  then return 0  /*number too low?*/
+         if !.x==1                                      then return 1  /*a known prime. */
+         if x// 2==0  then return 0;    if x//3==0      then return 0  /*÷ by  2;÷by  3?*/
+         parse var x '' -1 _;           if _==5         then return 0  /*last digit a 5?*/
+         if x// 7==0  then return 0;    if x//11==0     then return 0  /*÷ by  7;÷by 11?*/
+         if x//13==0  then return 0;    if x//17==0     then return 0  /*÷ by 13;÷by 17?*/
+         if x//19==0  then return 0;    if x//23==0     then return 0  /*÷ by 19;÷by 23?*/
+           do j=29  by 6  until j*j>x;  if x//j==0      then return 0  /*not a prime.   */
+                                        if x//(j+2)==0  then return 0  /* "  "   "      */
+           end   /*j*/
+         !.x=1;                return 1          /*indicate that  X  is a prime number. */
+/*──────────────────────────────────────────────────────────────────────────────────────*/
+isSemiPrime: procedure expose !.;  parse arg x;          if x<4  then return 0
+
+                           do i=2  for 2;  if x//i==0  then if isPrime(x%i)  then return 1
+                                                                             else return 0
+                           end   /*i*/
+                                                                             /*    ___  */
+               do   j=5  by 6  until j*j>x                                   /* > √ x  ?*/
+                 do k=j  by 2  for 2;  if x//k==0  then  if isPrime(x%k)  then return 1
+                                                                          else return 0
+                 end   /*k*/                     /* [↑]  see if 2nd factor is prime or ¬*/
+               end     /*j*/                     /* [↑]  J is never a multiple of three.*/
+         return 0

Task/Semiprime/Racket/semiprime-1.rkt

@@ -0,0 +1,15 @@
+#lang racket
+(require math)
+
+(define (pair-factorize n)
+  "Return all two-number factorizations of a number"
+  (let ([up-limit (integer-sqrt n)])
+    (map (λ (x) (list x (/ n x)))
+	 (filter (λ (x) (<= x up-limit)) (divisors n)))))
+
+(define (semiprime n)
+  "Determine if a number is semiprime i.e. a product of two primes.
+Check if any pair of complete factors consists of primes."
+  (for/or ((pair (pair-factorize n)))
+    (for/and ((el pair))
+      (prime? el))))

Task/Semiprime/Racket/semiprime-2.rkt

@@ -0,0 +1,12 @@
+#lang racket
+(require math)
+
+(define (semiprime n)
+  "Alternative implementation.
+Check if there are two prime factors whose product is the argument
+or if there is a single prime factor whose square is the argument"
+  (let ([prime-factors (factorize n)])
+    (or (and (= (length prime-factors) 1)
+	     (= (expt (caar prime-factors) (cadar prime-factors)) n))
+	(and (= (length prime-factors) 2)
+	     (= (foldl (λ (x y) (* (car x) y)) 1 prime-factors) n)))))

Task/Semiprime/Raku/semiprime-1.raku

@@ -0,0 +1,14 @@
+sub is-semiprime (Int $n --> Bool) {
+    not $n.is-prime and
+        .is-prime given
+        $n div first $n %% *, flat grep &is-prime, 2 .. *;
+}
+
+use Test;
+my @primes = flat grep &is-prime, 2 .. 100;
+for ^5 {
+    nok is-semiprime([*] my @f1 = @primes.roll(1)), ~@f1;
+    ok  is-semiprime([*] my @f2 = @primes.roll(2)), ~@f2;
+    nok is-semiprime([*] my @f3 = @primes.roll(3)), ~@f3;
+    nok is-semiprime([*] my @f4 = @primes.roll(4)), ~@f4;
+}

Task/Semiprime/Raku/semiprime-2.raku

@@ -0,0 +1,38 @@
+sub is-semiprime ( Int $n where * > 0 ) {
+    return False if $n.is-prime;
+    my $factor = find-factor( $n );
+    return True if $factor.is-prime && ( $n div $factor ).is-prime;
+    False;
+}
+
+sub find-factor ( Int $n, $constant = 1 ) {
+    my $x      = 2;
+    my $rho    = 1;
+    my $factor = 1;
+    while $factor == 1 {
+        $rho *= 2;
+        my $fixed = $x;
+        for ^$rho {
+            $x = ( $x * $x + $constant ) % $n;
+            $factor = ( $x - $fixed ) gcd $n;
+            last if 1 < $factor;
+        }
+    }
+    $factor = find-factor( $n, $constant + 1 ) if $n == $factor;
+    $factor;
+}
+
+INIT my $start = now;
+
+# Infinite list of semiprimes
+constant @semiprimes = lazy gather for 4 .. * { .take if .&is-semiprime };
+
+# Show the semiprimes < 100
+say 'Semiprimes less than 100:';
+say @semiprimes[^ @semiprimes.first: * > 100, :k ], "\n";
+
+# Check individual integers, or in this case, a range
+my $s = 2⁹⁷ - 1;
+say "Is $_ semiprime?: ", .&is-semiprime for $s .. $s + 30;
+
+say 'elapsed seconds: ', now - $start;

Task/Semiprime/Ring/semiprime.ring

@@ -0,0 +1,24 @@
+prime = 1679
+decomp(prime)
+
+func decomp nr
+x = ""
+sum = 0
+for i = 1 to nr
+    if isPrime(i) and nr % i = 0
+       sum = sum + 1
+       x = x + string(i) + " * " ok
+    if i = nr and sum = 2
+       x2 = substr(x,1,(len(x)-2))
+       see string(nr) + " = " + x2 + "is semiprime" + nl
+    but i = nr and sum != 2 see string(nr) + " is not semiprime" + nl ok
+next
+
+func isPrime n
+     if n < 2 return false ok
+     if n < 4 return true ok
+     if n % 2 = 0 and n != 2 return false ok
+     for d = 3 to sqrt(n) step 2
+         if n % d = 0 return false ok
+     next	
+     return true

Task/Semiprime/Ruby/semiprime-1.rb

@@ -0,0 +1,12 @@
+require 'prime'
+# 75.prime_division # Returns the factorization.75 divides by 3 once and by 5 twice => [[3, 1], [5, 2]]
+
+class Integer
+  def semi_prime?
+    prime_division.sum(&:last) == 2
+  end
+end
+
+p 1679.semi_prime? # true
+p ( 1..100 ).select( &:semi_prime? )
+# [4, 6, 9, 10, 14, 15, 21, 22, 25, 26, 33, 34, 35, 38, 39, 46, 49, 51, 55, 57, 58, 62, 65, 69, 74, 77, 82, 85, 86, 87, 91, 93, 94, 95]

Task/Semiprime/Ruby/semiprime-2.rb

@@ -0,0 +1,5 @@
+def semiprime(n)
+  `factor #{n}`.split.size == 3
+end
+n = 2**72 - 1   #4722366482869645213695
+(n-50..n).each { |n| puts "#{n} -> #{semiprime(n)}" }

Task/Semiprime/Run-BASIC/semiprime.basic

@@ -0,0 +1,17 @@
+function semiprime$(n)
+    a = 2
+    c = 0
+    while c < 3 and n > 1
+        if n mod a = 0 then
+            n = n / a
+            c = c + 1
+        else
+            a = a + 1
+        end if
+    wend
+    if c = 2 then semiprime$ = "True" else semiprime$ = "False"
+end function
+
+for i = 0 to 64
+    print i; chr$(9); semiprime$(i)
+next i

Task/Semiprime/Rust/semiprime-1.rust

@@ -0,0 +1,56 @@
+extern crate primal;
+
+fn isqrt(n: usize) -> usize {
+    (n as f64).sqrt() as usize
+}
+
+fn is_semiprime(mut n: usize) -> bool {
+    let root = isqrt(n) + 1;
+    let primes1 = primal::Sieve::new(root);
+    let mut count = 0;
+
+    for i in primes1.primes_from(2).take_while(|&x| x < root) {
+        while n % i == 0 {
+            n /= i;
+            count += 1;
+        }
+        if n == 1 {
+            break;
+        }
+    }
+
+    if n != 1 {
+        count += 1;
+    }
+    count == 2
+}
+
+#[test]
+fn test1() {
+    assert_eq!((2..10).filter(|&n| is_semiprime(n)).count(), 3);
+}
+
+#[test]
+fn test2() {
+    assert_eq!((2..100).filter(|&n| is_semiprime(n)).count(), 34);
+}
+
+#[test]
+fn test3() {
+    assert_eq!((2..1_000).filter(|&n| is_semiprime(n)).count(), 299);
+}
+
+#[test]
+fn test4() {
+    assert_eq!((2..10_000).filter(|&n| is_semiprime(n)).count(), 2_625);
+}
+
+#[test]
+fn test5() {
+    assert_eq!((2..100_000).filter(|&n| is_semiprime(n)).count(), 23_378);
+}
+
+#[test]
+fn test6() {
+    assert_eq!((2..1_000_000).filter(|&n| is_semiprime(n)).count(), 210_035);
+}

Task/Semiprime/Rust/semiprime-2.rust

@@ -0,0 +1,12 @@
+fn is_semiprime(n: usize) -> bool {
+    fn iter(x: usize, start: usize, count: usize) -> usize {
+        if count > 2 {return count} // break for semi_prime
+        let limit = (x as f64).sqrt().ceil() as usize;
+        match (start..=limit).skip_while(|i| x % i > 0).next() {
+            Some(v) => iter(x / v, v, count + 1),
+            None => if x < 2 { count }
+                    else { count + 1 }
+        }
+    }
+    iter(n, 2, 0) == 2
+}

Task/Semiprime/Scala/semiprime.scala

@@ -0,0 +1,20 @@
+object Semiprime extends App {
+
+  def isSP(n: Int): Boolean = {
+    var nf: Int = 0
+    var l = n
+    for (i <- 2 to l/2) {
+      while (l % i == 0) {
+        if (nf == 2) return false
+        nf +=1
+        l /= i
+      }
+    }
+    nf == 2
+  }
+
+  (2 to 100) filter {isSP(_) == true} foreach {i => print("%d ".format(i))}
+  println
+  1675 to 1681 foreach {i => println(i+" -> "+isSP(i))}
+
+}

Task/Semiprime/Seed7/semiprime.seed7

@@ -0,0 +1,27 @@
+$ include "seed7_05.s7i";
+
+const func boolean: semiPrime (in var integer: n) is func
+  result
+    var boolean: isSemiPrime is TRUE;
+  local
+    var integer: p is 2;
+    var integer: f is 0;
+  begin
+    while f < 2 and p**2 <= n do
+      while n rem p = 0 do
+        n := n div p;
+        incr(f);
+      end while;
+      incr(p);
+    end while;
+    isSemiPrime := f + ord(n > 1) = 2;
+  end func;
+
+const proc: main is func
+  local
+    var integer: v is 0;
+  begin
+    for v range 1675 to 1680 do
+      writeln(v <& " -> " <& semiPrime(v));
+    end for;
+  end func;

Task/Semiprime/Sidef/semiprime-1.sidef

@@ -0,0 +1,2 @@
+say is_semiprime(2**128 + 1)   #=> true
+say is_semiprime(2**256 - 1)   #=> false