A382786 Numbers k such that 5^k + k is prime.

7954, 22102, 33054, 135156

Offset: 1

Author

Nico Puada, Apr 24 2025

Keywords

• nonn
• hard
• more

Comments

All terms must end in the digit 2, 4, 6 or 8, otherwise 5^k + k is divisible by 2 or 5, which is not prime. - Jakub Buczak, May 04 2025

Crossrefs

Cf. A104745, A052007, A057900, A057909, A058046.

Programs

Mathematica

Select[Range[35000], PrimeQ[5^# + #] &] (* Nico Puada, Apr 24 2025 *)

Extensions

a(4) corrected by Jakub Buczak, May 04 2025