43 lines
821 B
ObjectPascal
43 lines
821 B
ObjectPascal
function IsPrime(n: int64): boolean;
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begin
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if (n = 2) or (n = 3) then Result := true
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else if (n <= 1) or ((n mod 2) = 0) or ((n mod 3) = 0) then Result := false
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else
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begin
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var i := 5;
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Result := False;
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while i <= trunc(sqrt(n)) do
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begin
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if ((n mod i) = 0) or ((n mod (i + 2)) = 0) then exit;
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i += 6;
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end;
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Result := True;
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end;
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end;
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function Factorial(n: integer): int64;
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begin
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Result := 1;
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for var i := 2 to n do Result *= i;
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end;
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begin
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var found := 0;
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var i := 1;
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while found < 10 do
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begin
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var fact := Factorial(i);
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if IsPrime(fact - 1) then
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begin
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writeln(i:2, '! - 1 = ', fact - 1);
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found += 1;
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end;
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if IsPrime(fact + 1) then
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begin
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writeln(i:2, '! + 1 = ', fact + 1);
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found += 1;
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end;
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i += 1;
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end;
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end.
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