0,2

Table of n, a(n) for n=0..81.

G.f.: theta_3(q)^2*theta_3(q^4), where theta_3() is the Jacobi theta function. - Ilya Gutkovskiy, Aug 01 2018

t0:=Array(0..10000, 0); M:=15;

for i from -M to M do for j from -M to M do for k from -M to M do

t1:=i^2+j^2+4*k^2; t0[t1]:=t0[t1]+1; od: od: od:

[seq(t0[i], i=0..100)];

x^2+y^2+k*z^2: A005875, A014455, A034933, A169784.

Sequence in context: A228048 A016705 A245592 * A133657 A121455 A227033

Adjacent sequences: A169780 A169781 A169782 * A169784 A169785 A169786

nonn

N. J. A. Sloane, May 12 2010

approved