OFFSET
1,1
COMMENTS
a(6), a(7) and a(8) correspond to probable primes.
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
MATHEMATICA
Select[Range[3000], PrimeQ[(15^# + 1) / 16] &] (* Vincenzo Librandi, Oct 29 2017 *)
PROG
(Prime95) PRP=1, 15, 551927, 1, 0, 0, "16"
(PARI) isok(n) = (denominator(p=(15^n+1)/16)==1) && isprime(p); \\ Michel Marcus, Oct 29 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Sep 15 2000
EXTENSIONS
a(6) from Paul Bourdelais, Mar 15 2010
a(7) from Paul Bourdelais, Mar 16 2010
a(8) from Paul Bourdelais, Jul 03 2013
a(9)-a(10) from Paul Bourdelais, Jul 08 2024
STATUS
approved