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 A128345 Numbers n such that (8^n - 5^n)/3 is prime. 19
 2, 19, 1021, 5077, 34031, 46099, 65707 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All terms are primes. No further terms up to 5000 - Harvey P. Dale, Mar 23 2011 a(8) > 10^5 - Robert Price, Dec 22 2012 LINKS MATHEMATICA k=8; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n, 1, 200}] Select[Range[5000], PrimeQ[(8^#-5^#)/3]&]  (* Harvey P. Dale, Mar 23 2011 *) PROG (PARI) is(n)=isprime((8^n-5^n)/3) \\ Charles R Greathouse IV, Feb 17 2017 CROSSREFS Cf. A062572, A128344, A128346, A128347, 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: A024228 A015191 A165937 * A013052 A012956 A012976 Adjacent sequences:  A128342 A128343 A128344 * A128346 A128347 A128348 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Feb 27 2007 EXTENSIONS a(4)-a(7) from Robert Price, Dec 22 2012 STATUS approved

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