OFFSET
-4,3
LINKS
Seiichi Manyama, Table of n, a(n) for n = -4..10000
H. Cohn, A. Kumar, S. Miller, D. Radchenko, M. Viazovska, The sphere packing problem in dimension 24, Annals of Mathematics, 185 (3) (2017), 1017-1033.
Wikipedia, Sphere packing
EXAMPLE
Let q = exp(Pi i t).
theta_2(q)^4 = 16*q + 64*q^3 + ... .
theta_4(q)^4 = 1 - 8*q + 24*q^2 - 32*q^3 + ... .
delta = q^2 - 24*q^4 + 252*q^6 - 1472*q^8 + ... .
(7 * theta_4(q)^20 * theta_2(q)^8 + 7 * theta_4(q)^24 * theta_2(q)^4 + 2 * theta_4(q)^28)/delta^2
= 2*q^(-4) - 464*q^(-2) + 172128 - 3670016*q + 47238464*q^2 - 459276288*q^3 + ... .
CROSSREFS
KEYWORD
sign
AUTHOR
Seiichi Manyama, Sep 16 2018
STATUS
approved