Find squares n where n+1 is prime: Difference between revisions
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Dr-neptune (talk | contribs) (rm (require racket)) |
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676</pre> |
676</pre> |
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=={{header| |
=={{header|OCaml}}== |
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<syntaxhighlight lang="ocaml">let is_prime n = |
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let rec test x = |
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x * x > n || n mod x <> 0 && n mod (x + 2) <> 0 && test (x + 6) |
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in if n < 5 then n lor 1 = 3 else n land 1 <> 0 && n mod 3 <> 0 && test 5 |
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let seq_squares = |
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let rec next n a () = Seq.Cons (n, next (n + a) (a + 2)) in |
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next 0 1 |
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let () = |
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let cond n = is_prime (succ n) in |
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seq_squares |> Seq.take_while ((>) 1000) |> Seq.filter cond |
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|> Seq.iter (Printf.printf " %u") |> print_newline</syntaxhighlight> |
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{{out}} |
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<pre> 1 4 16 36 100 196 256 400 576 676</pre> |
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=={{header|PARI/GP}}== |
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This is not terribly efficient, but it does show off the issquare and isprime functions. |
This is not terribly efficient, but it does show off the issquare and isprime functions. |
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