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 A128347 Numbers k such that (11^k - 5^k)/6 is prime. 26
 5, 41, 149, 229, 263, 739, 3457, 20269, 98221 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All terms are primes. a(10) > 10^5. - Robert Price, Jan 24 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)/6) \\ Charles R Greathouse IV, Feb 17 2017 CROSSREFS Cf. A062572, A128344, A128345, A128346, A128348, A128349, A128350, A128351, A128352, A128353, A128354. Cf. A004061, A082182, A121877, A059802. Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342. Sequence in context: A142101 A102265 A262340 * A056905 A105412 A271017 Adjacent sequences:  A128344 A128345 A128346 * A128348 A128349 A128350 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Feb 27 2007 EXTENSIONS a(7)-a(9) from Robert Price, Jan 24 2013 STATUS approved

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