A220701 Numbers k such that k^3 + 3*k + 3^k is prime.

1, 2, 4, 5, 7, 17, 22, 47, 155, 167, 203, 277, 469, 629, 890, 1427, 4507, 5705, 6095, 9808, 10108, 12797, 16184, 31535, 33575

Offset: 1

Author

Vincenzo Librandi, Jan 07 2013

Keywords

• nonn
• more

Comments

a(26) > 10^5. - Michael S. Branicky, Oct 25 2024

Crossrefs

Cf. A220509.

Programs

Mathematica

Select[Range[10000], PrimeQ[#^3 + 3*# + 3^#]&]

PARI

is(n)=ispseudoprime(n^3+3*n+3^n) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(21)-a(25) from Michael S. Branicky, Jul 13 2023