A216576 - OEIS

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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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..31.

Blair Kelly, Factorizations of Fibonacci and Lucas numbers

CROSSREFS

Cf. A000032, A001606.

Sequence in context: A182246 A118248 A132679 * A116617 A091996 A085262

Adjacent sequences: A216573 A216574 A216575 * A216577 A216578 A216579

KEYWORD

nonn

AUTHOR

V. Raman, Sep 08 2012

STATUS

approved