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 A128030 Numbers n such that (16^n - 3^n)/13 is prime. 27
 2, 3, 31, 467, 1747, 29683 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All terms are primes. No other terms < 100,000. LINKS MATHEMATICA k=13; Select[ Prime[ Range[1, 200] ], PrimeQ[ ((k+3)^# - 3^#)/k ]& ] PROG (PARI) is(n)=isprime((16^n-3^n)/13) \\ Charles R Greathouse IV, Feb 17 2017 CROSSREFS Cf. A028491 = numbers n such that (3^n - 1)/2 is prime. Cf. A057468 = numbers n such that 3^n - 2^n is prime. Cf. A059801 = numbers n such that 4^n - 3^n is prime. Cf. A121877 = numbers n such that (5^n - 3^n)/2 is a prime. Cf. A128024, A128025, A128026, A128027, A128028, A128029, A128031, A128032. Sequence in context: A054551 A049065 A274609 * A239593 A214658 A217761 Adjacent sequences:  A128027 A128028 A128029 * A128031 A128032 A128033 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Feb 11 2007 EXTENSIONS 1747 from Farideh Firoozbakht, Apr 08 2007 Added a(6)=29683 by Robert Price, Sep 13 2011 STATUS approved

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Last modified June 25 17:47 EDT 2019. Contains 324353 sequences. (Running on oeis4.)