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