A228130 Numbers n such that (18^n + 5^n)/23 is prime.

61, 227, 233, 239, 613, 2213, 7507, 13691

Offset

1,1

Comments

All terms are primes.

a(9) > 10^5.

Links

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

Mathematica

k=18; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 9592}]

Prog

(PARI) is(n)=ispseudoprime((18^n+5^n)/23) \\ Charles R Greathouse IV, Jun 13 2017

Crossrefs

Cf. A057184, A128353, A225397, A227046.

Sequence in context: A038643 A273364 A297731 * A142267 A034863 A251312

Adjacent sequences: A228127 A228128 A228129 * A228131 A228132 A228133

Keyword

hard,more,nonn

Author

Robert Price, Aug 11 2013

Status

approved