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A345402
Numbers k such that (42^k-1)/41 is prime.
0
2, 1319, 337081
OFFSET
1,1
COMMENTS
These are the repunit primes in base 42.
EXAMPLE
2 is a member since (42^2-1)/41 = 43 is prime.
MATHEMATICA
Do[ If[ PrimeQ[ (42^n-1)/41], Print[n]], {n, 2, 400000}]
PROG
(PARI) is(n)=isprime((42^n-1)/41)
CROSSREFS
Cf. A218745.
Sequence in context: A078170 A062663 A295187 * A298757 A020526 A247821
KEYWORD
nonn,hard,more,bref
AUTHOR
Paul Bourdelais, Sep 28 2021
STATUS
approved