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

Author

V. Raman, Sep 08 2012

Keywords

• nonn

Links

• Blair Kelly, Factorizations of Fibonacci and Lucas numbers

Crossrefs

Cf. A000032, A001606.