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A103640 Expansion of theta_4(q)^4 - theta_2(q)^4, where theta_2 and theta_4 are the Jacobi theta series. 1
1, -24, 24, -96, 24, -144, 96, -192, 24, -312, 144, -288, 96, -336, 192, -576, 24, -432, 312, -480, 144, -768, 288, -576, 96, -744, 336, -960, 192, -720, 576, -768, 24, -1152, 432, -1152, 312, -912, 480, -1344, 144, -1008, 768, -1056, 288, -1872 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

LINKS

C. Pache, Shells of selfdual lattices viewed as spherical designs

Eric Weisstein's World of Mathematics, Eisenstein Series

FORMULA

G.f.: theta_4(q)^4 - theta_2(q)^4.

PROG

(PARI) a(n)=if(n<1, n==0, (-1)^n*24*sumdiv(n, d, d%2*d))

CROSSREFS

Sequence in context: A040553 A022358 A122505 * A004011 A056465 A056455

Adjacent sequences:  A103637 A103638 A103639 * A103641 A103642 A103643

KEYWORD

sign

AUTHOR

Ralf Stephan (ralf(AT)ark.in-berlin.de), Feb 18 2005

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Last modified February 17 02:31 EST 2012. Contains 205978 sequences.