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A057187
Numbers n such that (21^n+1)/22 is a prime.
14
3, 5, 7, 13, 37, 347, 17597, 59183, 80761, 210599, 394579
OFFSET
1,1
COMMENTS
Some of the larger terms correspond to probable primes.
LINKS
H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
Paul Bourdelais, A Generalized Repunit Conjecture [From Paul Bourdelais, Mar 24 2010]
PROG
(Prime95) PRP=1, 21, 394579, 1, 0, 0, "22"
CROSSREFS
Sequence in context: A369433 A075557 A244452 * A163080 A141414 A236464
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 15 2000
EXTENSIONS
a(7) from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(8) corresponds to a probable prime discovered by Paul Bourdelais, Mar 22 2010
a(9) corresponds to a probable prime discovered by Paul Bourdelais, Mar 24 2010
a(10) corresponds to a probable prime discovered by Paul Bourdelais, Aug 30 2013
a(11) corresponds to a probable prime discovered by Paul Bourdelais, Oct 23 2018
STATUS
approved