login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A289209 Coefficients in expansion of E_4^3/E_6^2. 5
1, 1728, 1700352, 1332930816, 939690602496, 624182333927040, 399031077924476928, 248370528839869094400, 151578005556161702559744, 91116938989182168182098368, 54119528875319902426524072960, 31833210323194251819350736777984 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..365

FORMULA

G.f.: 1 + 1728 * q * Product_{k>=1} (1-q^k)^24 / E_6^2.

G.f.: (E_4*E_8)/(E_6*E_6) = (E_8*E_8)/(E_6*E_10). - Seiichi Manyama, Jun 29 2017

a(n) = 1728 * A289417(n - 1) for n > 0. - Seiichi Manyama, Jul 08 2017

a(n) ~ c * exp(2*Pi*n) * n, where c = 2.747700206704861755142526128354171788550012833617513654955480535522... - Vaclav Kotesovec, Jul 08 2017

MATHEMATICA

nmax = 20; CoefficientList[Series[(1 + 240*Sum[DivisorSigma[3, k]*x^k, {k, 1, nmax}])^3 / (1 - 504*Sum[DivisorSigma[5, k]*x^k, {k, 1, nmax}])^2, {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 08 2017 *)

CROSSREFS

Cf. A004009 (E_4), A013973 (E_6), A289063, A289210, A289417.

E_{k+2}/E_k: A288261 (k=4, 8), A288840 (k=6).

Sequence in context: A002519 A052068 A289210 * A114767 A165134 A013797

Adjacent sequences:  A289206 A289207 A289208 * A289210 A289211 A289212

KEYWORD

nonn

AUTHOR

Seiichi Manyama, Jun 28 2017

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 11 19:09 EST 2017. Contains 295919 sequences.