A377839 Numbers k such that (25^k - 2^k)/23 is prime.

11, 199, 509, 857, 42841

Offset

1,1

Comments

The definition implies that k must be a prime.

a(6) > 10^5.

Links

Table of n, a(n) for n=1..5.

P. Bourdelais, A Generalized Repunit Conjecture.

J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.

H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.

H. Lifchitz, Mersenne and Fermat primes field

Eric Weisstein's World of Mathematics, Repunit.

Mathematica

Select[Prime[Range[10000]], PrimeQ[(25^# - 2^#)/23] &]

Crossrefs

Cf. A062587, A062589, A127996, A127997, A128344, A204940, A217320, A225807, A229542, A375161, A375236, A377031.

Sequence in context: A034831 A142362 A140534 * A112733 A088295 A305316

Adjacent sequences: A377836 A377837 A377838 * A377840 A377843 A377844

Keyword

nonn,hard,more

Author

Robert Price, Nov 09 2024

Status

approved