%I #12 Jun 21 2022 04:29:00
%S 0,1,2,6,12,13,17,19,24,29,31,34,38,47,83,102,109,127,131,193,271,307,
%T 323,397,419,431,433,449,461,467,479,493,509,614,643,646,653,673,899,
%U 1069,1091,1346
%N Numbers k such that the k-th Fibonacci number can be written in the form a^2 + 7*b^2.
%C These Fibonacci numbers F(k) have no prime factors congruent to 3, 5 or 6 (mod 7) to an odd power. Also the power of 2 is not 1.
%H Blair Kelly, <a href="http://mersennus.net/fibonacci">Factorizations of Fibonacci and Lucas numbers</a>
%Y Cf. A020670.
%K nonn
%O 1,3
%A _V. Raman_, Sep 08 2012