login
Number of integer solutions to a^2 + b^2 + 2*c^2 + 7*d^2 = n.
14

%I #11 Oct 06 2018 12:00:16

%S 1,4,6,8,12,8,8,18,14,24,40,32,40,40,32,28,36,64,46,72,72,16,56,40,40,

%T 88,72,80,82,64,44,64,86,96,128,144,64,64,136,44,136,160,80,144,128,

%U 120,92,128,104,164,158,96,168,80,144,160,168,108,104,232,108,168,192,82

%N Number of integer solutions to a^2 + b^2 + 2*c^2 + 7*d^2 = n.

%C a(n) > 0 for n >= 0.

%H Seiichi Manyama, <a href="/A320128/b320128.txt">Table of n, a(n) for n = 0..10000</a>

%F G.f.: theta_3(q)^2 * theta_3(q^2) * theta_3(q^7).

%Y Cf. A097057, A320124, A320125, A320126, A320127.

%K nonn

%O 0,2

%A _Seiichi Manyama_, Oct 06 2018