A182413 Number of primes of the form 4^n - 2^k - 1 with 0 < k < n.

0, 1, 2, 1, 2, 3, 2, 2, 5, 5, 4, 4, 2, 0, 2, 3, 0, 6, 3, 3, 4, 3, 2, 4, 0, 1, 2, 3, 0, 5, 1, 3, 4, 1, 2, 6, 2, 2, 1, 6, 0, 2, 3, 1, 5, 2, 5, 3, 4, 2, 6, 5, 1, 3, 4, 6, 3, 4, 2, 1, 4, 2, 2, 3, 6, 2, 4, 4, 7, 4, 2, 8, 2, 0, 4, 4, 1, 1, 5, 2, 5, 2, 4, 10, 1, 0, 5

Offset

1,3

Comments

In the first 3100 terms: if a(n) > 0 its average is about 3; for less than 9% of n is a(n) = 0.

Links

Pierre CAMI, Table of n, a(n) for n = 1..3100

Mathematica

Table[Length[Select[Range[n - 1], PrimeQ[4^n - 2^# - 1] &]], {n, 100}] (* T. D. Noe, May 03 2012 *)

Crossrefs

Sequence in context: A159974 A143866 A155002 * A296664 A209126 A272377

Adjacent sequences: A182410 A182411 A182412 * A182414 A182415 A182416

Keyword

nonn

Author

Pierre CAMI, Apr 28 2012

Status

approved