A357612 Numbers k such that 1 + 2^k*k^3 is prime.

1, 5, 41, 202, 281, 394, 1157, 1211, 1816, 9845, 19780, 50800, 98621, 101945

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 17 2022

Keywords

• nonn
• more
• hard

Examples

			1 is in this sequence because 1 + 2^1*1^3 = 5 is prime;
5 is in this sequence because 1 + 2^5*5^3 = 4001 is prime.
		

Crossrefs

Cf. A000040, A005849, A058780.

Programs

Magma

[n: n in [1..2000] | IsPrime(1+2^n*n^3)];

Mathematica

Select[Range[2000], PrimeQ[1 + 2^# * #^3] &] (* Amiram Eldar, Nov 17 2022 *)

Extensions

a(11)-a(12) from Amiram Eldar, Nov 17 2022

a(13)-a(14) from Michael S. Branicky, May 16 2023