A216561 Numbers n such that the n-th Fibonacci number is prime, but cannot be written in the form a^2 + 5*b^2.

3, 4, 5, 7, 13, 17, 23, 43, 47, 83, 137, 433, 4723, 5387, 9677, 30757, 50833, 201107, 931517, 1049897, 1285607, 1636007

Offset

1,1

Links

Table of n, a(n) for n=1..22.

Blair Kelly, Factorizations of Fibonacci and Lucas numbers

Crossrefs

Cf. A000045, A001605.

Sequence in context: A325422 A190213 A216574 * A192269 A284618 A101759

Adjacent sequences: A216558 A216559 A216560 * A216562 A216563 A216564

Keyword

nonn

Author

V. Raman, Sep 08 2012

Status

approved