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 A128340 Numbers n such that (11^n + 5^n)/16 is prime. 19
 7, 11, 181, 421, 2297, 2797, 4129, 4139, 7151, 29033 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All terms are primes. a(11) > 10^5. - Robert Price, Feb 09 2013 LINKS MATHEMATICA k=11; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}] PROG (PARI) is(n)=isprime((11^n+5^n)/16) \\ Charles R Greathouse IV, Feb 17 2017 CROSSREFS Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128341, A128342, A128343. Cf. A004061, A082182, A121877, A059802. Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354. Sequence in context: A038543 A145953 A154303 * A106716 A292791 A106818 Adjacent sequences:  A128337 A128338 A128339 * A128341 A128342 A128343 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Feb 27 2007 EXTENSIONS a(5)-a(10) from Robert Price, Feb 09 2013 STATUS approved

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Last modified January 19 06:37 EST 2020. Contains 331033 sequences. (Running on oeis4.)