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A241921
Numbers k such that (15^k - 4^k)/11 is prime.
0
2, 1097, 2243, 2857, 4357, 6803, 20747, 24571
OFFSET
1,1
COMMENTS
All terms are prime.
a(9) > 10^5.
a(1) is trivially prime, the remainder are probable primes.
MATHEMATICA
Select[Prime[Range[1, 100000]], PrimeQ[(15^# - 4^#)/11]&]
PROG
(PARI) is(n)=ispseudoprime((15^n-4^n)/11) \\ Charles R Greathouse IV, Jun 13 2017
KEYWORD
nonn,hard,more
AUTHOR
Robert Price, May 01 2014
STATUS
approved