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 A128028 Numbers n such that (13^n - 3^n)/10 is prime. 29
 7, 31, 41, 269, 283, 7333, 8803 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All terms are primes. No other terms exist < 100,000. LINKS MATHEMATICA k=10; Select[ Prime[ Range[1, 200] ], PrimeQ[ ((k+3)^# - 3^#)/k ]& ] PROG (PARI) is(n)=isprime((13^n-3^n)/10) \\ 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, A128029, A128030, A128031, A128032. Sequence in context: A276741 A000696 A171733 * A000921 A185004 A172490 Adjacent sequences:  A128025 A128026 A128027 * A128029 A128030 A128031 KEYWORD hard,more,nonn AUTHOR Alexander Adamchuk, Feb 11 2007 EXTENSIONS One more term from Farideh Firoozbakht, Apr 03 2007 a(7)=8803 from Robert Price, Aug 12 2011 STATUS approved

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Last modified October 23 15:13 EDT 2018. Contains 316528 sequences. (Running on oeis4.)