A014704 Expansion of ((theta_2)^4+(theta_3)^4)/(Delta_24)^2.

1, 72, 2400, 52576, 870732, 11739984, 134825216, 1359259200, 12290396058, 101268020984, 769721861376, 5449376818656, 36216000728200, 227395735413552, 1356190070338560, 7717657198319936, 42069113073665703, 220400042813587800

Offset

0,2

References

J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 105.

Links

Table of n, a(n) for n=0..17.

Mathematica

s = (EllipticTheta[2, 0, q]^4 + EllipticTheta[3, 0, q]^4)/QPochhammer[q]^48 + O[q]^20; CoefficientList[s, q] (* Jean-François Alcover, Dec 03 2015 *)

Prog

(PARI) {a(n)=local(A); if(n<0, 0, A=x*O(x^n); polcoeff( sum(k=1, n, 24*sumdiv(k, d, d%2*d)*x^k, 1+A)/eta(x+A)^48, n))} /* Michael Somos, Feb 15 2006 */

Crossrefs

Sequence in context: A347566 A277532 A341556 * A260582 A035118 A017788

Adjacent sequences: A014701 A014702 A014703 * A014705 A014706 A014707

Keyword

nonn

Author

N. J. A. Sloane

Status

approved