A216550 Numbers n such that (2^n+1)/3 is prime and can be written in the form a^2 + 3*b^2.

7, 13, 19, 31, 43, 61, 79, 127, 199, 313, 2617, 10501, 12391, 14479, 138937, 141079, 986191

Offset

1,1

Comments

The exponent is congruent to 1 mod 3.

Links

Table of n, a(n) for n=1..17.

Samuel S. Wagstaff, Jr. The Cunningham Project

Crossrefs

Cf. A000978.

Sequence in context: A040058 A172057 A173176 * A267803 A240971 A023255

Adjacent sequences: A216547 A216548 A216549 * A216551 A216552 A216553

Keyword

nonn

Author

V. Raman, Sep 08 2012

Status

approved