# Greetings from The On-Line Encyclopedia of Integer Sequences! http://oeis.org/ Search: id:a191660 Showing 1-1 of 1 %I A191660 #15 Oct 30 2016 18:48:23 %S A191660 2,1,4,4,13,14,36,48,96,141,261,386,676,1030,1706,2619,4230,6462, %T A191660 10219,15568,24165,36627,56103,84428,127873,191201,286663,425802, %U A191660 632973,933995,1377774,2020424,2959438,4314109,6278824,9100908,13167388,18983295,27313916,39177636,56080228,80048942,114030110,162018938,229741517,325000341,458854803,646409612 %N A191660 Second differences of A000219. %D A191660 G. Almkvist, The differences of the number of plane partitions, Manuscript, circa 1991. %F A191660 a(n) ~ 2^(13/36) * Zeta(3)^(31/36) * exp(1/12 + 3*Zeta(3)^(1/3)*n^(2/3)/2^(2/3)) / (A * sqrt(3*Pi) * n^(49/36)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant. - _Vaclav Kotesovec_, Oct 30 2016 %t A191660 Differences[CoefficientList[Series[Product[(1-x^k)^-k, {k,1,64}], {x,0,64}],x],2] (* _Harvey P. Dale_, Jun 19 2011 *) %t A191660 nmax = 50; Drop[CoefficientList[Series[(1-x)^2 * Product[1/(1-x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x], 2] (* _Vaclav Kotesovec_, Oct 30 2016 *) %Y A191660 Cf. A000219, A191659, A191661. %K A191660 nonn %O A191660 0,1 %A A191660 _N. J. A. Sloane_, Jun 10 2011 # Content is available under The OEIS End-User License Agreement: http://oeis.org/LICENSE