A216555 Numbers n such that the n-th Lucas number is prime, but cannot be written in the form a^2 + 3*b^2.

0, 5, 7, 8, 13, 16, 31, 37, 47, 53, 61, 71, 79, 503, 613, 863, 7741, 19469, 81671, 94823, 344293, 532277, 631181, 637751, 651821

Offset

1,2

Links

Table of n, a(n) for n=1..25.

Blair Kelly, Factorizations of Fibonacci and Lucas numbers

Crossrefs

Cf. A000032, A001606.

Sequence in context: A066001 A320391 A047477 * A288151 A242408 A171952

Adjacent sequences: A216552 A216553 A216554 * A216556 A216557 A216558

Keyword

nonn

Author

V. Raman, Sep 08 2012

Status

approved