A216576 Numbers n such that n-th Lucas number is prime, but cannot be written in the form a^2 + 10*b^2.

0, 2, 4, 7, 8, 11, 16, 19, 31, 47, 71, 79, 503, 863, 4787, 5851, 8467, 10691, 12251, 13963, 36779, 44507, 56003, 81671, 94823, 148091, 202667, 574219, 616787, 637751, 692147

Offset: 1

Author

V. Raman, Sep 08 2012

Keywords

• nonn

Links

• Blair Kelly, Factorizations of Fibonacci and Lucas numbers

Crossrefs

Cf. A000032, A001606.