OFFSET
1,2
COMMENTS
The first term greater than 1 such that b^32+1 is also a prime is a(173) = 7072833120, see A235390. - Alex Ratushnyak, Jan 02 2014, comment extended by Jeppe Stig Nielsen, Aug 18 2020
The term a(2)=2 corresponds to the five classical Fermat primes. - Jeppe Stig Nielsen, Aug 18 2020
LINKS
Jeppe Stig Nielsen, Table of n, a(n) for n = 1..1000 (calculated by Yves Gallot).
Yves Gallot, GFP (Generalized Fermat Progressions) / gfp5, software for calculating this sequence.
MATHEMATICA
Do[ If[ PrimeQ[n + 1] && PrimeQ[n^2 + 1] && PrimeQ[n^4 + 1] && PrimeQ[n^8 + 1] && PrimeQ[n^16 + 1], Print[n]], {n, 1, 10^7}]
Select[Range[21*10^5], AllTrue[#^2^Range[0, 4]+1, PrimeQ]&] (* The program generates the first six terms of the sequence. *) (* Harvey P. Dale, Jun 02 2024 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, May 13 2002
EXTENSIONS
a(7)-a(24) from Donovan Johnson, Dec 02 2009
a(25)-a(28) from Alex Ratushnyak, Jan 02 2014
STATUS
approved