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A228130
Numbers n such that (18^n + 5^n)/23 is prime.
1
61, 227, 233, 239, 613, 2213, 7507, 13691
OFFSET
1,1
COMMENTS
All terms are primes.
a(9) > 10^5.
MATHEMATICA
k=18; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 9592}]
PROG
(PARI) is(n)=ispseudoprime((18^n+5^n)/23) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Robert Price, Aug 11 2013
STATUS
approved