A182425 a(n) the largest integer K such that (prime(n+1)-1)^(2^k)+1 for 0<=k<=K is prime.

4, 3, 2, 1, 0, 2, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 2, 0, 0, 0, 0, 0

Offset

1,1

Comments

This sequence is a generalized reference to Fermat primes.

Links

Table of n, a(n) for n=1..87.

Mathematica

Table[k = 0; While[PrimeQ[(Prime[n+1] - 1)^(2^k) + 1], k++];  k - 1, {n, 100}] (* T. D. Noe, Apr 28 2012 *)

Crossrefs

Cf. A182199.

Sequence in context: A023446 A258447 A066440 * A071692 A307335 A030586

Adjacent sequences: A182422 A182423 A182424 * A182426 A182427 A182428

Keyword

nonn

Author

Thomas Ordowski, Apr 28 2012

Status

approved