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 A008699 Theta series of Niemeier lattice of type A_6^4. 4
 1, 168, 192528, 16815456, 397786704, 4630192560, 34416639936, 187487122368, 814893967440, 2975532395976, 9486531825120, 27053035734816, 70486174680768, 169930998266736, 384163653863808 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 REFERENCES J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 407. LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 FORMULA This series is the q-expansion of (49*E_4(z)^3 + 23*E_6(z)^2)/72. - Daniel D. Briggs, Nov 25 2011 MATHEMATICA terms = 15; E4[q_] := 1 + 240 Sum[DivisorSigma[3, n]*q^(2 n), {n, 1, terms}]; E6[q_] := 1 - 504 Sum[DivisorSigma[5, n]*q^(2 n), {n, 1, terms}]; s = 49/72 E4[q]^3 + 23/72 E6[q]^2 + O[q]^(3 terms); Partition[ CoefficientList[s, q], 2][[All, 1]][[1 ;; terms]] (* Jean-François Alcover, Jul 06 2017 *) CROSSREFS Cf. A004009, A013973. Cf. A008688 - A008698, A008700 - A008704. Sequence in context: A185404 A146200 A159394 * A223125 A003797 A297048 Adjacent sequences: A008696 A008697 A008698 * A008700 A008701 A008702 KEYWORD nonn AUTHOR N. J. A. Sloane STATUS approved

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Last modified November 28 08:03 EST 2023. Contains 367394 sequences. (Running on oeis4.)