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A033720
Product theta3(q^d); d | 8.
13
1, 2, 2, 4, 4, 4, 8, 8, 8, 10, 12, 12, 16, 20, 16, 24, 24, 20, 26, 20, 24, 32, 24, 24, 32, 30, 28, 40, 32, 20, 48, 32, 24, 48, 36, 48, 52, 36, 40, 56, 48, 52, 64, 44, 48, 84, 48, 48, 96, 50, 62, 72, 56, 68, 80, 72, 64
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
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
Sequence in context: A124340 A071165 A137688 * A033728 A033744 A133389
KEYWORD
nonn
STATUS
approved