A288246 Numbers k such that 8*k^3 + 81 is prime.

1, 4, 8, 10, 11, 13, 20, 26, 29, 34, 35, 43, 46, 50, 53, 56, 68, 70, 71, 85, 86, 94, 95, 98, 125, 130, 131, 139, 149, 154, 160, 161, 163, 169, 170, 178, 184, 194, 196, 199, 208, 215, 229, 239, 259, 266, 269, 271, 280, 283, 286, 290, 298, 305, 313

Offset: 1

Author

Vincenzo Librandi, Jun 07 2017

Keywords

• nonn
• easy

Examples

			a(1) = 1 because 8*1 + 81 = 89 is prime.
a(2) = 4 because 8*4^3 + 81 = 593 is prime.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..4400

Crossrefs

Cf. A155722: Numbers k such that 2*k + 9 is prime.

Cf. A002971: Numbers k such that 4*k^2 + 25 is prime.

Programs

Magma

[n: n in [0..500] |IsPrime(8*n^3+81)];

Mathematica

Select[Range[500], PrimeQ[8 #^3 + 81] &]