A216572 Numbers n such that the n-th Lucas number is prime, but cannot be written in the form a^2 + 6*b^2.

0, 2, 5, 7, 8, 13, 16, 17, 19, 31, 37, 41, 47, 53, 61, 71, 79, 113, 353, 503, 613, 617, 863, 1097, 1361, 4793, 5851, 7741, 8467, 13963, 19469, 81671, 89849, 94823, 140057, 159521, 183089, 344293, 443609, 532277, 574219, 631181, 637751, 651821

Offset

1,2

Links

Table of n, a(n) for n=1..44.

Blair Kelly, Factorizations of Fibonacci and Lucas numbers

Crossrefs

Cf. A000032, A001606.

Sequence in context: A299326 A280848 A190900 * A020674 A243171 A005624

Adjacent sequences: A216569 A216570 A216571 * A216573 A216574 A216575

Keyword

nonn

Author

V. Raman, Sep 08 2012

Status

approved