A216968 Numbers n such that 2*n^2 + 3 is prime.

0, 1, 2, 5, 7, 8, 22, 23, 28, 37, 40, 43, 47, 50, 55, 62, 70, 82, 83, 92, 98, 103, 107, 110, 113, 118, 125, 127, 128, 133, 160, 170, 175, 187, 197, 202, 203, 205, 208, 212, 247, 250, 253, 265, 268, 275, 278, 320, 322, 352, 370, 373, 377, 380, 407, 412, 413, 415

Offset

1,3

Links

Zak Seidov, Table of n, a(n) for n = 1..10000

Maple

a:= proc(n) option remember; local k;
      for k from 1+ `if`(n=1, -1, a(n-1))
        while not isprime(2*k^2 + 3) do od; k
    end:
seq(a(n), n=1..100);  # Alois P. Heinz, Sep 23 2012

Mathematica

p=3; s3={}; Do[If[PrimeQ[p + 2 n^2], AppendTo[s3, n]], {n, 0, 500}]
Select[Range[0, 500], PrimeQ[2#^2+3]&] (* Harvey P. Dale, Nov 24 2013 *)

Prog

(Magma) [n: n in [0..500] | IsPrime(2*n^2+3)]; // Bruno Berselli, Sep 21 2012
(PARI) select(n->isprime(2*n^2+3), vector(2000, n, n-1)) /* Joerg Arndt, Sep 21 2012 */

Crossrefs

Cf. A201473 (associated primes), A216898.

Sequence in context: A238364 A342730 A227445 * A088757 A308637 A267693

Adjacent sequences: A216965 A216966 A216967 * A216969 A216970 A216971

Keyword

nonn,easy

Author

Zak Seidov, Sep 20 2012

Status

approved