OFFSET
0,2
COMMENTS
Also number of integer solutions to a^2 +2*b^2 + 4*c^2 + 8*d^2 = n.
REFERENCES
J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p 102 eq 9.
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..10000
J. Liouville, Sur la forme x^2 + 2y^2 + 4z^2 + 8t^2, Journal de mathématiques pures et appliquées 2e série, tome 6 (1861), p. 409-416.
FORMULA
Liouville gives an explicit formula for a(n).
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved