A216566 Numbers n such that the n-th Lucas number is prime, but cannot be written in the form a^2 + b^2.

2, 4, 5, 8, 11, 16, 17, 41, 47, 53, 71, 113, 353, 503, 617, 863, 1097, 1361, 4787, 4793, 10691, 12251, 19469, 36779, 44507, 56003, 81671, 89849, 94823, 140057, 148091, 159521, 183089, 202667, 443609, 532277, 616787, 631181, 637751, 651821, 692147

Offset: 1

Author

V. Raman, Sep 08 2012

Keywords

• nonn

Links

• Blair Kelly, Factorizations of Fibonacci and Lucas numbers

Crossrefs

Cf. A000032, A001606.