1,1

Base 7 repunit primes. - Paul Bourdelais (paul.bourdelais(AT)gd-ais.com), Aug 31 2007

a(7)=35201 is a probable prime with trial factoring to 7e12 and Fermat base 2 primality test. - Paul Bourdelais (paul.bourdelais(AT)gd-ais.com), Aug 31 2007

J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.

H. Dubner, Generalized repunit primes, Math. Comp., 61 (1993), 927-930.

J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.

S. S. Wagstaff, Jr., The Cunningham Project

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

H. Lifchitz, Mersenne and Fermat primes field

For[n = 1, n <= 20000, n++, If[PrimeQ[(7^n - 1)/6 ], Print[n]]] - Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 09 2006

Sequence in context: A117437 A106046 A117527 this_sequence A005764 A099974 A117077

Adjacent sequences: A004060 A004061 A004062 this_sequence A004064 A004065 A004066

nonn,hard

njas

a(6) from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 09 2005

a(7) from Paul Bourdelais (paul.bourdelais(AT)gd-ais.com), Aug 31 2007