OFFSET
0,2
COMMENTS
Here "norm" is being used in the sense of L_2 norm, as opposed to the definition in SPLAG. - N. J. A. Sloane, Sep 29 2007
REFERENCES
J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..500
FORMULA
a(n) = [x^(n^2)] theta_3(x)^10/(1 - x), where theta_3() is the Jacobi theta function. - Ilya Gutkovskiy, Apr 15 2018
EXAMPLE
To check that a(2) = 4541:
norm^2 # total
0 1 1
1 20 21
2 180 201
3 960 1161
4 3380 4541
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Edited by N. J. A. Sloane, Sep 29 2007
STATUS
approved