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!)
A023912 Theta series of A_21 lattice. 0
1, 462, 43890, 1501500, 23437722, 198944592, 1114627514, 4828206900, 17160463320, 52574485502, 143000133276, 353652649308, 808266398940, 1728870130680, 3496186881264, 6732994928660, 12429951473478 (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. 110.

LINKS

Table of n, a(n) for n=0..16.

MATHEMATICA

terms = 17; f[q_] = LatticeData["A21", "ThetaSeriesFunction"][-I*Log[q]/Pi]; s = f[q] + O[q]^(2 terms); Partition[CoefficientList[s, q] // Round, 2][[All, 1]][[1 ;; terms]] (* Jean-François Alcover, Jul 06 2017 *)

CROSSREFS

Sequence in context: A194718 A267283 A289349 * A027565 A035847 A140905

Adjacent sequences:  A023909 A023910 A023911 * A023913 A023914 A023915

KEYWORD

nonn

AUTHOR

N. J. A. Sloane.

EXTENSIONS

More terms from Robert.Harley(AT)inria.fr, see A023902.

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 November 26 17:52 EST 2021. Contains 349343 sequences. (Running on oeis4.)