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A274711
Numbers n such that 5^n + 4^(n+1) is prime.
0
0, 2, 6, 34, 282, 3662, 87206
OFFSET
1,2
COMMENTS
a(8) > 10^5.
EXAMPLE
6 is a member since 5^6 + 4^7 = 15625 + 16384 = 32009 which is a prime number.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[5^# + 4^(# + 1)] &]
PROG
(PARI) lista(nn) = for(n=0, nn, if(ispseudoprime(5^n + 4^(n+1)), print1(n, ", "))); \\ Altug Alkan, Jul 03 2016
KEYWORD
nonn,more
AUTHOR
Robert Price, Jul 03 2016
STATUS
approved