43 lines
1.1 KiB
Text
43 lines
1.1 KiB
Text
func IsPrime(N); \Return 'true' if N > 2 is a prime number
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int N, I;
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[if (N&1) = 0 \even number\ then return false;
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for I:= 3 to sqrt(N) do
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[if rem(N/I) = 0 then return false;
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I:= I+1;
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];
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return true;
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];
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func CircPrime(N0); \Return 'true' if N0 is a circular prime
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int N0, N, Digits, Rotation, I, R;
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[N:= N0;
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Digits:= 0; \count number of digits in N
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repeat Digits:= Digits+1;
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N:= N/10;
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until N = 0;
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N:= N0;
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for Rotation:= 0 to Digits-1 do
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[if not IsPrime(N) then return false;
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N:= N/10; \rotate least sig digit into high end
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R:= rem(0);
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for I:= 0 to Digits-2 do
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R:= R*10;
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N:= N+R;
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if N0 > N then \reject N0 if it has a smaller prime rotation
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return false;
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];
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return true;
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];
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int Counter, N;
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[IntOut(0, 2); ChOut(0, ^ ); \show first circular prime
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Counter:= 1;
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N:= 3; \remaining primes are odd
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loop [if CircPrime(N) then
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[IntOut(0, N); ChOut(0, ^ );
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Counter:= Counter+1;
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if Counter >= 19 then quit;
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];
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N:= N+2;
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];
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]
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