A241921 Numbers k such that (15^k - 4^k)/11 is prime.

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

Offset

1,1

Comments

All terms are prime.

a(9) > 10^5.

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

Links

Table of n, a(n) for n=1..8.

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

Cf. A004063, A028491, A057468, A059801, A121877, A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032, A210506, A128347, A225955, A062581.

Sequence in context: A282293 A252358 A135618 * A340290 A119554 A272246

Adjacent sequences: A241918 A241919 A241920 * A241922 A241923 A241924

Keyword

nonn,hard,more

Author

Robert Price, May 01 2014

Status

approved