%I #14 Jun 21 2022 04:29:54
%S 1,3,4,5,7,16,17,19,21,32,35,37,49,51,53,64,71,76,80,85,97,101,113,
%T 119,128,133,147,148,160,181,199,211,212,224,229,241,245,259,263,293,
%U 307,311,320,323,343,352,353,355,357,371,401,416,421,464,497,503,524,544,577,593,595
%N Numbers k such that the k-th Lucas number can be written in the form a^2 + 7*b^2.
%C These Lucas numbers L(k) have no prime factors congruent to 3 (mod 7) or 5 (mod 7) or 6 (mod 7) to an odd power. Also the power of 2 is not 1.
%H V. Raman, <a href="/A216433/b216433.txt">Table of n, a(n) for n = 1..82</a>
%H Blair Kelly, <a href="http://mersennus.net/fibonacci">Factorizations of Fibonacci and Lucas numbers</a>
%K nonn
%O 1,2
%A V. Raman, Sep 08 2012