Data update

Task/Factorial-primes/PascalABC.NET/factorial-primes.pas

@@ -0,0 +1,42 @@
+function IsPrime(n: int64): boolean;
+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
+    var i := 5;
+    Result := False;
+    while i <= trunc(sqrt(n)) do
+    begin
+      if ((n mod i) = 0) or ((n mod (i + 2)) = 0) then exit;
+      i += 6;
+    end;
+    Result := True;
+  end;
+end;
+
+function Factorial(n: integer): int64;
+begin
+  Result := 1;
+  for var i := 2 to n do Result *= i;
+end;
+
+begin
+  var found := 0;
+  var i := 1;
+  while found < 10 do
+  begin
+    var fact := Factorial(i);
+    if IsPrime(fact - 1) then
+    begin
+      writeln(i:2, '! - 1 = ', fact - 1);
+      found += 1;
+    end;
+    if IsPrime(fact + 1) then
+    begin
+      writeln(i:2, '! + 1 = ', fact + 1);
+      found += 1;
+    end;
+    i += 1;
+  end;
+end.