A335805 Numbers b such that b^(2^i) + 1 is prime for i = 0...6.

1, 2072005925466, 5082584069416, 12698082064890, 29990491969260, 46636691707050, 65081025897426, 83689703895606, 83953213480290, 105003537341346, 105699143244090, 107581715369910, 111370557491826, 111587899569066, 128282713771996, 133103004825210

Offset: 1

Author

Jeppe Stig Nielsen, Aug 14 2020

Keywords

• nonn

Comments

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

The first term greater than 1 such that b^(2^7) + 1 is also prime, is 240164550712338756, see A337364. - Jeppe Stig Nielsen, Aug 25 2020

Links

• Jeppe Stig Nielsen, Table of n, a(n) for n = 1..4603 (up to a(n) = A337364(2), calculated by _Kellen Shenton_)
• Yves Gallot, GFP (Generalized Fermat Progressions) / gfp7, software for calculating this sequence.

Crossrefs

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