A337364 Numbers b such that b^(2^i) + 1 is prime for i = 0...7.

1, 240164550712338756, 3686834112771042790, 6470860179642426900, 7529068955648085700, 10300630358100537120, 16776829808789151280, 17622040391833711780, 19344979062504927000, 23949099004395080026, 25348938242408650240, 30262840543567048476, 35628481193915651646

Offset: 1

Author

Jeppe Stig Nielsen, Aug 25 2020

Keywords

• nonn

Comments

Explicitly, for each b, the eight numbers b+1, b^2+1, b^4+1, b^8+1, b^16+1, b^32+1, b^64+1, and b^128+1 must be primes (generalized Fermat primes).

Links

• Jeppe Stig Nielsen, Table of n, a(n) for n = 1..31 (found by Rob Gahan)
• Yves Gallot, GFP (Generalized Fermat Progressions) / gfp8, software for calculating this sequence.

Crossrefs

Cf. A006093, A019434, A056993, A070325, A070655, A070689, A070694, A090872, A235390, A335805.

Extensions

a(10)-a(12) from Jeppe Stig Nielsen, Sep 04 2020

a(13) found by Rob Gahan added by Jeppe Stig Nielsen, Feb 15 2021