A241921 - OEIS

A241921

Numbers k such that (15^k - 4^k)/11 is prime.

2, 1097, 2243, 2857, 4357, 6803, 20747, 24571

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OFFSET

1,1

COMMENTS

All terms are prime.

a(9) > 10^5.

a(1) is trivially prime, the remainder are probable primes.

LINKS

MATHEMATICA

Select[Prime[Range[1, 100000]], PrimeQ[(15^# - 4^#)/11]&]

PROG

(PARI) is(n)=ispseudoprime((15^n-4^n)/11) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

KEYWORD

nonn,hard,more

AUTHOR

Robert Price, May 01 2014

STATUS

approved