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A128353 Numbers n such that (18^n - 5^n)/13 is prime. 19
2, 3, 19, 23, 31, 37, 251, 283, 977, 28687, 32993 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are primes.

a(12) > 10^5. - Robert Price, Aug 10 2013

LINKS

Table of n, a(n) for n=1..11.

MATHEMATICA

k=18; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]

PROG

(PARI) is(n)=isprime((18^n-5^n)/13) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128354. Cf. A004061, A082182, A121877, A059802. Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342.

Sequence in context: A092925 A082012 A059675 * A217691 A109418 A038957

Adjacent sequences:  A128350 A128351 A128352 * A128354 A128355 A128356

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Feb 27 2007

EXTENSIONS

a(10)-a(11) from Robert Price, Aug 10 2013

STATUS

approved

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Last modified January 21 05:39 EST 2020. Contains 331104 sequences. (Running on oeis4.)