A236929 - OEIS

%I #17 Sep 23 2019 09:05:57

%S 1,4,4,0,4,12,16,16,4,20,44,16,16,24,32,64,4,8,52,16,44,32,48,48,16,

%T 84,56,64,32,56,176,32,4,64,72,112,52,56,80,64,44,72,128,32,48,188,96,

%U 48,16,68,244,128,56,56,160,176,32,128,120,112,176,88,128,144,4,200

%N Number of integer solutions to a^2 + b^2 + 5*c^2 + 5*d^2 = n.

%H Seiichi Manyama, <a href="/A236929/b236929.txt">Table of n, a(n) for n = 0..10000</a>

%H J. Liouville, <a href="http://sites.mathdoc.fr/JMPA/afficher_notice.php?id=JMPA_1861_2_6_A46_0">Sur la forme x^2 + 2y^2 + 4z^2 + 8t^2</a>, Journal de mathématiques pures et appliquées 2e série, tome 6 (1861), p. 409-416.

%F G.f.: theta_3(q)^2*theta_3(q^5)^2, where theta_3() is the Jacobi theta function. - _Ilya Gutkovskiy_, Aug 03 2018

%p See A236924.

%K nonn

%O 0,2

%A _N. J. A. Sloane_, Feb 15 2014