A197119 Number of k such that (2^k+1)*2^n+1 is prime with 0 < k < n+1.

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

Offset

1,3

Comments

As n increases sum a(n) from 1 to n / n tends to 2.00.

Links

Pierre CAMI, Table of n, a(n) for n = 1..3000

Prog

(PARI) a(n) = sum(k=1, n, isprime((2^k+1)*2^n+1)); \\ Michel Marcus, Sep 21 2019

Crossrefs

Cf. A197116, A197117, A197118.

Sequence in context: A307226 A263390 A231354 * A124377 A144190 A239689

Adjacent sequences: A197116 A197117 A197118 * A197120 A197121 A197122

Keyword

nonn

Author

Pierre CAMI, Oct 11 2011

Status

approved