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URL: https://oeis.org/A272296

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A272296
Numbers n such that 5^n-4^(n-1) is prime.
0
3, 11, 25, 341, 1827, 2581, 4475, 11157, 41141, 64721
OFFSET
1,1
COMMENTS
a(11) > 10^5.
EXAMPLE
3 is a member since 5^3 - 4^2 = 125 - 16 = 109 which is a prime number.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[5^# - 4^(# - 1)] &]
PROG
(PARI) is(n)=ispseudoprime(5^n-4^(n-1)) \\ Charles R Greathouse IV, Jun 13 2017
KEYWORD
nonn,more
AUTHOR
Robert Price, Apr 27 2016
STATUS
approved