A128354 Numbers k such that (19^k - 5^k)/14 is prime.

5, 17, 31, 59, 373, 643, 2843, 5209, 85009

Offset

1,1

Comments

All terms are primes.

a(10) > 10^5. - Robert Price, Jul 22 2013

Links

Table of n, a(n) for n=1..9.

Mathematica

k=19; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]

Prog

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

Crossrefs

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

Cf. A004061, A082182, A121877, A059802.

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

Sequence in context: A031370 A147434 A147336 * A078654 A083364 A273499

Adjacent sequences: A128351 A128352 A128353 * A128355 A128356 A128357

Keyword

hard,more,nonn

Author

Alexander Adamchuk, Feb 27 2007

Extensions

a(7)-a(9) from Robert Price, Jul 22 2013

Status

approved