A028512 Character of extremal vertex operator algebra of rank 16.

1, 496, 69752, 2115008, 34670620, 394460000, 3499148224, 25817318016, 165011628166, 939112182480, 4853601292512, 23116070653888, 102602164703800, 428200065370144, 1692346392263680, 6371305129660032

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

References

• G. Hoehn, Selbstduale Vertexoperatorsuperalgebren und das Babymonster, Bonner Mathematische Schriften, Vol. 286 (1996), 1-85.

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 0..10000 (terms 0..1000 from Seiichi Manyama)
• G. Hoehn (gerald(AT)math.ksu.edu), Selbstduale Vertexoperatorsuperalgebren und das Babymonster, Doctoral Dissertation, Univ. Bonn, Jul 15 1995 (pdf, ps).

Crossrefs

Cf. A000521 (j(q)).

(q*j(q))^(k/24): A289397 (k=-1), A106205 (k=1), A289297 (k=2), A289298 (k=3), A289299 (k=4), A289300 (k=5), A289301 (k=6), A289302 (k=7), A007245 (k=8), A289303 (k=9), A289304 (k=10), A289305 (k=11), A161361 (k=12), this sequence (k=16), A028513 (k=32), A028514 (k=40), A028515 (k=48).

Programs

Mathematica

CoefficientList[Series[(QPochhammer[x, x^2]^8 + 256*x/QPochhammer[x, x^2]^16)^2, {x, 0, 20}], x] (* Vaclav Kotesovec, Jul 15 2017 *)
CoefficientList[Series[(65536 + x*QPochhammer[-1, x]^24)^2 / (2*QPochhammer[-1, x])^16, {x, 0, 20}], x] (* Vaclav Kotesovec, Sep 23 2017 *)

Formula

Square of A007245.

(q*j(q))^(2/3) where j(q) is the elliptic modular invariant. - Seiichi Manyama, Jul 15 2017

a(n) ~ exp(4*Pi*sqrt(2*n/3)) / (6^(1/4)*n^(3/4)). - Vaclav Kotesovec, Jul 15 2017