

A057180


Numbers n such that (14^n + 1)/15 is a prime.


15




OFFSET

1,1


COMMENTS

Of the Repunit primes with base 21<=b<=21, base=14 is the most "unlucky" with a normalized prime occurrence rate of 0.86289. The Generalized Repunit Conjecture (see below) states that this will eventually improve and converge to Euler's Constant (~0.55).  Paul Bourdelais, Mar 10 2014


LINKS

Table of n, a(n) for n=1..6.
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


PROG

(Prime95) PRP=1, 14, 1091401, 1, 0, 0, "15"


CROSSREFS

Sequence in context: A081338 A142981 A120272 * A137612 A092802 A062207
Adjacent sequences: A057177 A057178 A057179 * A057181 A057182 A057183


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Sep 15 2000


EXTENSIONS

a(5) from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 05 2008
a(6)=1091401 is a probable prime discovered by Paul Bourdelais, Mar 10 2014


STATUS

approved



