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A309410 Numbers k such that (41^k + 1)/42 is prime. 0
17, 691, 113749 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Larger terms correspond to probable primes.

LINKS

Table of n, a(n) for n=1..3.

P. Bourdelais, A Generalized Repunit Conjecture

MATHEMATICA

Do[p=Prime[n]; If[ PrimeQ[(41^p + 1)/42], Print[p]], {n, 1, 1000000}]

PROG

(PARI) is(n)=ispseudoprime((41^n+1)/42)

CROSSREFS

Sequence in context: A012157 A012137 A171198 * A201311 A012182 A012029

Adjacent sequences:  A309407 A309408 A309409 * A309411 A309412 A309413

KEYWORD

nonn,bref,hard,more

AUTHOR

Paul Bourdelais, Jul 29 2019

STATUS

approved

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Last modified August 7 04:39 EDT 2020. Contains 336274 sequences. (Running on oeis4.)