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A128341 Numbers n such that (12^n + 5^n)/17 is prime. 22
3, 5, 13, 347, 977, 1091, 4861, 4967, 34679 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are primes.

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

LINKS

Table of n, a(n) for n=1..9.

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

Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128342, A128343. Cf. A004061, A082182, A121877, A059802. Cf. A062572, A128344, A128345, A128346, A128347, A128348, A128349, A128350, A128351, A128352, A128353, A128354.

Sequence in context: A110407 A062698 A200769 * A177007 A227170 A028942

Adjacent sequences:  A128338 A128339 A128340 * A128342 A128343 A128344

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Feb 27 2007

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

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Last modified June 25 11:56 EDT 2019. Contains 324352 sequences. (Running on oeis4.)