0,2

Also the number of integer solutions (a_1, a_2, a_3) to the equation a_1^2 + 3*a_2^2 + 5*a_3^2 = n.

Seiichi Manyama, Table of n, a(n) for n = 0..10000

Eric Weisstein's World of Mathematics, Jacobi Theta Functions

Product_{k=1..m} theta_3(q^(2*k-1)): A000122 (m=1), A033716 (m=2), this sequence (m=3), A320240 (m=4).

Cf. A320078.

Sequence in context: A139213 A306079 A242860 * A033727 A033757 A320240

Adjacent sequences: A320236 A320237 A320238 * A320240 A320241 A320242

nonn

Seiichi Manyama, Oct 08 2018

approved