A128341 - OEIS

A128341

Numbers k such that (12^k + 5^k)/17 is prime.

3, 5, 13, 347, 977, 1091, 4861, 4967, 34679

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OFFSET

1,1

COMMENTS

All terms are primes.

a(10) > 10^5. - Robert Price, May 05 2013

LINKS

MATHEMATICA

k=12; Do[p=Prime[n]; f=(k^p+5^p)/(k+5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]

Select[Range[1100], PrimeQ[(12^#+5^#)/17]&] (* Harvey P. Dale, Jul 24 2012 *)

PROG

(PARI) is(n)=isprime((12^n+5^n)/17) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

KEYWORD

hard,more,nonn

AUTHOR

EXTENSIONS

Two more terms (a(7) and a(8)) from Harvey P. Dale, Jul 24 2012

a(9) from Robert Price, May 05 2013

STATUS

approved