Initial data commit

Task/Arithmetic-numbers/Factor/arithmetic-numbers.factor

@@ -0,0 +1,23 @@
+USING: combinators formatting grouping io kernel lists
+lists.lazy math math.functions math.primes math.primes.factors
+math.statistics math.text.english prettyprint sequences
+tools.memory.private ;
+
+: arith? ( n -- ? ) divisors mean integer? ;
+: larith ( -- list ) 1 lfrom [ arith? ] lfilter ;
+: arith ( m -- seq ) larith ltake list>array ;
+: composite? ( n -- ? ) dup 1 > swap prime? not and ;
+: ordinal ( n -- str ) [ commas ] keep ordinal-suffix append ;
+
+: info. ( n -- )
+    {
+        [ ordinal "%s arithmetic number: " printf ]
+        [ arith dup last commas print ]
+        [ commas "Number of composite arithmetic numbers <= %s: " printf ]
+        [ drop [ composite? ] count commas print nl ]
+    } cleave ;
+
+
+"First 100 arithmetic numbers:" print
+100 arith 10 group simple-table. nl
+{ 3 4 5 6 } [ 10^ info. ] each