OFFSET
1,1
COMMENTS
(28^1031+1)/29, a 1491-digit number, has now been certified prime with Primo.
a(8) > 10^5. - Robert Price, Jul 10 2013
LINKS
H. Dubner and T. Granlund, Primes of the Form (b^n+1)/(b+1), J. Integer Sequences, 3 (2000), #P00.2.7.
PROG
(PARI) isok(n) = (denominator(p=(28^n+1)/29)==1) && isprime(p); \\ Michel Marcus, Oct 29 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Rick L. Shepherd, May 22 2002
EXTENSIONS
a(7) from Robert Price, Jul 10 2013
a(8)=223381 corresponds to a probable prime discovered by Paul Bourdelais, Dec 23 2020
STATUS
approved