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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 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 May 20 20:16 EDT 2019. Contains 323426 sequences. (Running on oeis4.)