A125881 Numbers k for which k^3+k^2-1 is prime.

2, 4, 5, 6, 9, 11, 12, 14, 19, 22, 25, 26, 27, 29, 32, 34, 36, 37, 40, 44, 47, 49, 55, 60, 62, 64, 65, 69, 70, 71, 81, 82, 84, 89, 95, 97, 106, 107, 114, 119, 121, 125, 127, 132, 139, 140, 141, 144, 147, 155, 159, 161, 165, 172, 174, 179, 184, 190, 201, 204

Offset: 1

Author

Artur Jasinski, Dec 14 2006

Keywords

• nonn

Comments

Generating polynomial belongs to the family of irreducible polynomials (or trinomials) of the form x^n+x^(n-1)-1.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harvey P. Dale)

Crossrefs

Cf. A045546, A125882, A125883, A125884, A125885.

Programs

Mathematica

Do[If[PrimeQ[x^3 + x^2 - 1], Print[x]], {x, 1, 100}]
Select[Range[250], PrimeQ[#^3 + #^2 - 1] &] (* Harvey P. Dale, Jan 20 2015 *)

PARI

isok(n) = isprime(n^3+n^2-1); \\ Michel Marcus, Nov 08 2013

Extensions

More terms from Michel Marcus, Nov 08 2013