A169784 Number of solutions to a^2 + b^2 + 5*c^2 = n.

1, 4, 4, 0, 4, 10, 8, 8, 4, 12, 24, 0, 0, 16, 8, 16, 4, 8, 20, 0, 10, 16, 24, 8, 8, 44, 8, 0, 8, 16, 40, 16, 4, 16, 24, 0, 12, 32, 8, 16, 24, 16, 16, 0, 0, 50, 40, 8, 0, 28, 44, 0, 16, 16, 32, 40, 8, 32, 40, 0, 16, 32, 16, 24, 4, 48, 16, 0, 8, 16, 80, 16, 20, 40, 24, 0, 0, 16, 32, 32, 10, 36

Offset: 0

Author

N. J. A. Sloane, May 12 2010

Keywords

• nonn

Comments

a(n) = 0 for n of the form 4^i*(8*j+3), A055046. [Zak Seidov, May 12 2010]

Links

• Zak Seidov, Table of n,a(n) for n=0..1000

Crossrefs

x^2+y^2+k*z^2: A005875, A014455, A034933, A169783.

Formula

G.f.: theta_3(q)^2*theta_3(q^5), where theta_3() is the Jacobi theta function. - Ilya Gutkovskiy, Aug 01 2018