Concatenate two primes is also prime: Difference between revisions
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(Added XPL0 example.) |
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Found 128 such concatenated primes. |
Found 128 such concatenated primes. |
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</pre> |
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=={{header|XPL0}}== |
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<lang XPL0>func IsPrime(N); \Return 'true' if N is a prime number |
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int N, I; |
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[if N <= 1 then return false; |
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for I:= 2 to sqrt(N) do |
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if rem(N/I) = 0 then return false; |
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return true; |
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]; |
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char Set(9999+1); |
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int P1, P2, P, Count; |
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[for P:= 0 to 9999 do Set(P):= false; |
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for P1:= 0 to 99 do |
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if IsPrime(P1) then |
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for P2:= 0 to 99 do |
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if IsPrime(P2) then |
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[if P2 >= 10 then |
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P:= P1*100 + P2 |
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else P:= P1*10 + P2; |
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if IsPrime(P) then Set(P):= true; |
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]; |
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Count:= 0; |
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for P:= 0 to 9999 do |
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if Set(P) then |
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[IntOut(0, P); |
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Count:= Count+1; |
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if rem(Count/10) = 0 then CrLf(0) else ChOut(0, 9\tab\); |
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]; |
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CrLf(0); |
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IntOut(0, Count); |
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Text(0, " such concatenated primes found. |
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"); |
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]</lang> |
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{{out}} |
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<pre> |
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23 37 53 73 113 137 173 193 197 211 |
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223 229 233 241 271 283 293 311 313 317 |
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331 337 347 353 359 367 373 379 383 389 |
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397 433 523 541 547 571 593 613 617 673 |
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677 719 733 743 761 773 797 977 1117 1123 |
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1129 1153 1171 1319 1361 1367 1373 1723 1741 1747 |
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1753 1759 1783 1789 1913 1931 1973 1979 1997 2311 |
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2341 2347 2371 2383 2389 2917 2953 2971 3119 3137 |
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3167 3719 3761 3767 3779 3797 4111 4129 4153 4159 |
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4337 4373 4397 4723 4729 4759 4783 4789 5323 5347 |
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5923 5953 6113 6131 6143 6173 6197 6719 6737 6761 |
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6779 7129 7159 7331 7919 7937 8311 8317 8329 8353 |
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8389 8923 8929 8941 8971 9719 9743 9767 |
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128 such concatenated primes found. |
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</pre> |
</pre> |