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A128075
Numbers k such that (3^k + 19^k)/22 is prime.
12
3, 61, 71, 109, 9497, 36007, 50461, 66919
OFFSET
1,1
COMMENTS
All terms are primes.
a(9) > 10^5. - Robert Price, Jul 21 2013
MATHEMATICA
k=19; Do[ p=Prime[n]; f=(3^p+k^p)/(k+3); If[ PrimeQ[f], Print[p]], {n, 1, 9592} ]
PROG
(PARI) is(n)=isprime((3^n+19^n)/22) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
Cf. A007658 (numbers k such that (3^k + 1)/4 is prime).
Cf. A057469 (numbers k such that (3^k + 2^k)/5 is prime).
Cf. A122853 (numbers k such that (3^k + 5^k)/8 is prime).
Cf. A059801 (numbers k such that 4^k - 3^k is prime).
Cf. A121877 (numbers k such that (5^k - 3^k)/2 is prime).
Sequence in context: A093883 A203518 A297562 * A106883 A037209 A181505
KEYWORD
hard,more,nonn
AUTHOR
Alexander Adamchuk, Feb 14 2007
EXTENSIONS
a(5)-a(8) from Robert Price, Jul 21 2013
STATUS
approved