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 A029817 Average theta series of odd unimodular lattices of dimension 16 (multiplied by 17). 0
 17, 32, 4064, 70016, 528352, 2500032, 8892032, 26353408, 67637216, 153125024, 317504064, 623589504, 1156034176, 2007952576, 3346882816, 5470070016, 8657571808, 13130837568, 19446878048, 28603895680 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS H. H. Chan and C. Krattenthaler, Recent progress in the study of representations of integers as sums of squares, arXiv:math/0407061 [math.NT], 2004. FORMULA G.f.: 17 + 32 * Sum_{k >= 1} k^7*q^k/(1-(-q)^k). MATHEMATICA max = 20; s = 17 + 32*Sum[k^7*q^k/(1-(-q)^k), {k, 1, max}] + O[q]^max; CoefficientList[s, q] (* Jean-François Alcover, Dec 07 2015 *) PROG (PARI) a(n)=if(n<1, 17*(n==0), 32*sumdiv(n, d, d^7-2*if(d%4==2, (d/2)^7))) /* Michael Somos, Jul 16 2004 */ CROSSREFS Cf. A013955. Sequence in context: A043907 A173054 A162624 * A162504 A085255 A283395 Adjacent sequences:  A029814 A029815 A029816 * A029818 A029819 A029820 KEYWORD nonn AUTHOR STATUS approved

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Last modified January 17 23:37 EST 2020. Contains 330995 sequences. (Running on oeis4.)