Mersenne primes: Difference between revisions
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(→{{header|AppleScript}}: Added more efficient version. Corrected the original's <syntaxhighlight…> tags.) |
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2 ^ 19 - 1
2 ^ 31 - 1</pre>
=={{header|Delphi}}==
{{works with|Delphi|6.0}}
{{libheader|SysUtils,StdCtrls}}
<syntaxhighlight lang="Delphi">
function IsPrime(N: int64): boolean;
{Fast, optimised prime test}
var I,Stop: int64;
begin
if (N = 2) or (N=3) then Result:=true
else if (n <= 1) or ((n mod 2) = 0) or ((n mod 3) = 0) then Result:= false
else
begin
I:=5;
Stop:=Trunc(sqrt(N+0.0));
Result:=False;
while I<=Stop do
begin
if ((N mod I) = 0) or ((N mod (I + 2)) = 0) then exit;
Inc(I,6);
end;
Result:=True;
end;
end;
procedure MersennePrimes(Memo: TMemo);
var N: integer;
var Mn: int64;
begin
Memo.Lines.Add('2^N-1 Prime');
Memo.Lines.Add('--------------------' );
for N:=1 to 32 do
begin
Mn:=(1 shl N)-1;
if IsPrime(Mn) then
Memo.Lines.Add(Format('2^%d-1 %14.0n',[N,Mn+0.0]));
end;
end;
</syntaxhighlight>
{{out}}
<pre>
2^N-1 Prime
--------------------
2^2-1 3
2^3-1 7
2^5-1 31
2^7-1 127
2^13-1 8,191
2^17-1 131,071
2^19-1 524,287
2^31-1 2,147,483,647
</pre>
=={{header|F_Sharp|F#}}==
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