login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A047806 Duplicate of A008696. 0
1, 240, 190800, 16833600, 397680720, 4630540320, 34416204480, 187485916800, 814900050000, 2975524213680, 9486523478880, 27053074226880, 70486147972800, 169930956669600, 384163682797440, 820166912933760 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Original title: Theta series of Niemeier lattice of type A_9^2*D_6.

LINKS

Table of n, a(n) for n=0..15.

FORMULA

This series is the q-expansion of 13/18 E_4(z)^3 + 5/18 E_6(z)^2. Cf. A004009, A013973. - Daniel D. Briggs, Nov 25 2011

MATHEMATICA

terms = 16; 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 = 13/18 E4[q]^3 + 5/18 E6[q]^2 + O[q]^(3 terms); Partition[ CoefficientList[s, q], 2][[All, 1]][[1 ;; terms]] (* Jean-Fran├žois Alcover, Jul 06 2017 *)

CROSSREFS

Cf. A008696. - R. J. Mathar, Oct 18 2008

Sequence in context: A275459 A035281 A008696 * A184888 A158792 A270051

Adjacent sequences:  A047803 A047804 A047805 * A047807 A047808 A047809

KEYWORD

nonn,dead

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jul 05 2000

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 7 10:07 EDT 2021. Contains 343649 sequences. (Running on oeis4.)