OFFSET
1,1
COMMENTS
(12^1483 + 1)/13, a 1600-digit number, has now been certified prime with Primo. - Rick L. Shepherd, May 01 2002
LINKS
Paul Bourdelais, A Generalized Repunit Conjecture
J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
H. Lifchitz, Mersenne and Fermat primes field
Eric Weisstein's World of Mathematics, Repunit
MATHEMATICA
lst={}; Do[p=(12^n+1)/13; If[PrimeQ[p], AppendTo[lst, n]], {n, 7!}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 29 2008 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 15 2000
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(10) corresponds to a probable prime, discovered by Paul Bourdelais, Feb 08 2010
a(11) corresponds to a probable prime, discovered by Paul Bourdelais, Sep 21 2011
a(12) corresponds to a probable prime, discovered by Paul Bourdelais, Nov 13 2018
STATUS
approved