OFFSET
0,2
COMMENTS
a(n) > 0 for n >= 0.
REFERENCES
J. H. Conway, Universal quadratic forms and the fifteen theorem, Contemporary Mathematics 272 (1999), 23-26.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
FORMULA
G.f.: theta_3(q)^2 * theta_3(q^3) * theta_3(q^4).
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 06 2018
STATUS
approved