OFFSET
1,2
COMMENTS
A subsequence of A070694.
Conjecture: the sequence is infinite.
For n=4 and n=9, a(n)*2+1 is also a prime.
The first term greater than 1 such that k^(2^6) + 1 is also prime, is a(148) = 2072005925466, see A335805. - Jeppe Stig Nielsen, Aug 18 2020
LINKS
Jeppe Stig Nielsen, Table of n, a(n) for n = 1..101 (calculated by Yves Gallot (pers. communication), terms n = 2..94 from Martin Raab)
Yves Gallot, GFP (Generalized Fermat Progressions) / gfp6, software for calculating this sequence.
EXAMPLE
k=7072833120 is in the sequence because the following are six primes: 7072833121, 7072833120^2+1, k^4+1, k^8+1, k^16+1, k^32+1.
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Jan 09 2014
EXTENSIONS
a(1)=1 inserted by Jeppe Stig Nielsen, Aug 11 2020
STATUS
approved