A128343 Numbers k such that (14^k + 5^k)/19 is prime.

3, 7, 17, 79, 17477, 19319, 49549

Offset

1,1

Comments

All terms are primes.

a(8) > 10^5. - Robert Price, May 20 2013

Links

Table of n, a(n) for n=1..7.

Mathematica

k=14; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]

Prog

(PARI) is(n)=isprime((14^n+5^n)/19) \\ Charles R Greathouse IV, Feb 17 2017

Crossrefs

Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342.

Cf. A004061, A082182, A121877, A059802.

Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Sequence in context: A264765 A247196 A246764 * A106877 A041949 A222452

Adjacent sequences: A128340 A128341 A128342 * A128344 A128345 A128346

Keyword

hard,more,nonn

Author

Alexander Adamchuk, Feb 27 2007

Extensions

a(5)-a(7) from Robert Price, May 20 2013

Status

approved