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A128347 Numbers k such that (11^k - 5^k)/6 is prime. 26
5, 41, 149, 229, 263, 739, 3457, 20269, 98221 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are primes.

a(10) > 10^5. - Robert Price, Jan 24 2013

LINKS

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

MATHEMATICA

k=11; Do[p=Prime[n]; f=(k^p-5^p)/(k-5); If[ PrimeQ[f], Print[p] ], {n, 1, 100}]

PROG

(PARI) is(n)=isprime((11^n-5^n)/6) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Cf. A062572, A128344, A128345, A128346, A128348, A128349, A128350, A128351, A128352, A128353, A128354. Cf. A004061, A082182, A121877, A059802. Cf. A057171, A082387, A122853, A128335, A128336, A128337, A128338, A128339, A128340, A128341, A128342.

Sequence in context: A142101 A102265 A262340 * A056905 A105412 A271017

Adjacent sequences:  A128344 A128345 A128346 * A128348 A128349 A128350

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Feb 27 2007

EXTENSIONS

a(7)-a(9) from Robert Price, Jan 24 2013

STATUS

approved

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Last modified January 19 06:37 EST 2020. Contains 331033 sequences. (Running on oeis4.)