A216564 - OEIS

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A216564

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

%I #12 May 02 2013 13:10:54

%S 7,19,31,79,5851,8467,13963,574219

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

%H Blair Kelly, <a href="http://mersennus.net/fibonacci">Factorizations of Fibonacci and Lucas numbers</a>

%Y Cf. A000032, A001606.

%K nonn

%O 1,1

%A _V. Raman_, Sep 08 2012