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

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A105094 Expansion of 8 * (eta(q^2) / eta(q)^2)^8 in powers of q. 1
 8, 128, 1152, 7680, 42112, 200448, 855552, 3345408, 12166272, 41609856, 134973184, 418023936, 1242729984, 3561814784, 9877810176, 26587137024, 69636039808, 177877244160, 443991342720, 1084762764800, 2598075516672 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 (terms 0..200 from Vincenzo Librandi) Richard E. Borcherds, Automorphic forms with singularities on Grassmannians, arXiv:alg-geom/9609022, 1996-1997; Invent. Math. 132 (1998), 491-562. FORMULA Expansion of 8 / phi(-q)^8 in powers of q where phi() is a Ramanujan theta function. - Michael Somos, Jun 08 2012 a(n) ~ exp(2*Pi*sqrt(2*n)) / (2^(15/4) * n^(11/4)). - Vaclav Kotesovec, Nov 14 2015 EXAMPLE 8 + 128*q + 1152*q^2 + 7680*q^3 + 42112*q^4 + 200448*q^5 + 855552*q^6 + ... MAPLE gf:=8*product((1-q^(2*n))^8, n=1..100)/product((1-q^n)^16, n=1..100): s:=series(gf, q, 100): for k from 0 to 40 do printf(`%d, `, coeff(s, q, k)) od: # James A. Sellers, Apr 09 2005 MATHEMATICA QP = QPochhammer; s = 8*(QP[q^2]/QP[q]^2)^8 + O[q]^30; CoefficientList[s, q] (* Jean-François Alcover, Nov 14 2015 *) PROG (PARI) {a(n) = local(A); if( n<0, 0, A = x * O(x^n); polcoeff( 8 * eta(x^2 + A)^8 / eta(x + A)^16, n))} /* Michael Somos, Apr 09 2005 */ CROSSREFS Sequence in context: A061549 A303471 A301998 * A208711 A242355 A305519 Adjacent sequences:  A105091 A105092 A105093 * A105095 A105096 A105097 KEYWORD nonn,easy AUTHOR N. J. A. Sloane, Apr 07 2005 EXTENSIONS More terms from Michael Somos, Apr 07 2005 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.

Last modified December 1 09:39 EST 2021. Contains 349426 sequences. (Running on oeis4.)