A094210 Numbers k such that k^2 + 3k + 1 is a prime.

1, 2, 3, 4, 5, 7, 8, 9, 10, 12, 14, 15, 18, 19, 20, 23, 25, 27, 29, 30, 34, 37, 38, 40, 43, 44, 45, 47, 49, 52, 53, 54, 55, 58, 59, 63, 64, 65, 67, 69, 75, 82, 84, 85, 88, 92, 93, 95, 99, 100, 102, 113, 114, 119, 124, 125, 129, 130, 133, 137, 139, 140, 143, 144, 147, 148

Offset: 1

Author

Giovanni Teofilatto, May 27 2004

Keywords

• easy
• nonn

Links

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

Crossrefs

Cf. A002327, A002328, A028387.

Programs

Magma

[n: n in [0..200] | IsPrime(n^2 + 3*n + 1)]; // Vincenzo Librandi, Nov 11 2014

Mathematica

Select[ Range[150], PrimeQ[ #^2 + 3# + 1] &] (* Robert G. Wilson v, May 29 2004 *)

Formula

a(n) = A002328(n)-2. - R. J. Mathar, Aug 08 2012

Extensions

Edited and extended by Robert G. Wilson v, May 29 2004