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A327661
Least number k > n - 2 such that k*n^k - 1 is prime.
2
3, 2, 2, 3, 8, 19, 18, 7, 10, 11, 252, 43, 563528, 98, 14, 167, 18, 28, 410, 44, 200, 140, 29028, 124, 68, 79, 2420, 47, 26850, 63, 2454, 140, 42, 164, 38, 62, 740, 67, 448, 51, 84, 135, 404882, 43, 84, 140, 140, 115, 710, 2390, 46640, 261, 60, 72, 2064, 414
OFFSET
1,1
COMMENTS
Different version of A240235. Some authors, like Caldwell (link), require that k + 2 > n before they use the term generalized Woodall for a prime of form k*n^k - 1.
LINKS
EXAMPLE
To find a(11), consider numbers k*11^k - 1 where k > 9. The first time it is prime, is for k = 252, so a(11) = 252.
PROG
(PARI) for(b=1, +oo, for(k=b-1, +oo, if(ispseudoprime(k*b^k-1), print1(k, ", "); next(2))))
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Jeppe Stig Nielsen, Sep 21 2019
STATUS
approved