A216565 Numbers n such that the n-th Lucas number is prime, but cannot be written in the form a^2 + 5*b^2.

0, 2, 5, 7, 8, 11, 16, 17, 19, 37, 41, 47, 53, 71, 79, 113, 353, 503, 617, 863, 1097, 1361, 4787, 4793, 8467, 10691, 12251, 14449, 19469, 35449, 36779, 44507, 51169, 56003, 81671, 89849, 94823, 140057, 148091, 159521, 183089, 202667, 443609, 532277, 574219, 616787, 631181, 637751, 651821, 692147

Offset

1,2

Links

Table of n, a(n) for n=1..50.

Blair Kelly, Factorizations of Fibonacci and Lucas numbers

Crossrefs

Cf. A000032, A001606.

Sequence in context: A032724 A153308 A370856 * A285938 A325441 A192111

Adjacent sequences: A216562 A216563 A216564 * A216566 A216567 A216568

Keyword

nonn

Author

V. Raman, Sep 08 2012

Status

approved