A-M baby

Task/Lucas-Lehmer-test/DWScript/lucas-lehmer-test.dwscript

@@ -0,0 +1,26 @@
+function IsMersennePrime(p : Integer) : Boolean;
+var
+   i, s, m_p : Integer;
+begin
+   if p=2 then
+      Result:=True
+   else begin
+      m_p := (1 shl p)-1;
+      s := 4;
+      for i:=3 to p do
+         s:=(s*s-2) mod m_p;
+      Result:=(s=0);
+   end;
+end;
+
+const upperBound = Round(Log2(High(Integer))/2);
+
+PrintLn('Finding Mersenne primes in M[2..' + IntToStr(upperBound) + ']: ');
+Print('M2');
+
+var p : Integer;
+for p:=3 to upperBound step 2 do begin
+   if IsMersennePrime(p) then
+      Print(' M'+IntToStr(p));
+end;
+PrintLn('');