A156616 -id:A156616 - cp's OEIS frontend

A285675 Expansion of Product_{n>0} ((1-x^n)/(1+x^n))^n in powers of x.

1, -2, -2, 0, 6, 8, 4, -4, -18, -34, -32, -8, 36, 96, 144, 152, 94, -60, -294, -560, -760, -760, -460, 228, 1276, 2486, 3576, 4080, 3456, 1304, -2576, -7956, -13986, -19208, -21644, -19056, -9462, 8200, 33364, 63224, 92384, 112860, 114976, 88896, 26660, -74792

Offset: 0

Seiichi Manyama, Apr 30 2017

sign

Seiichi Manyama, Table of n, a(n) for n = 0..10000

Product_{n>0} ((1-x^n)/(1+x^n))^(n^m): A002448 (m=0), this sequence (m=1), A285988 (m=2), A285990 (m=3), A285991 (m=4).

Cf. A076577, A156616.

a(0) = 1, a(n) = -(2/n)*Sum_{k=1..n} A076577(k)*a(n-k) for n > 0.
G.f.: exp(Sum_{k>=1} (sigma_2(k) - sigma_2(2*k))*x^k/(2*k)). - Ilya Gutkovskiy, Apr 14 2019
G.f.: exp( - 2*Sum_{n >= 0} x^(2*n+1)/((2*n+1)*(1 - x^(2*n+1))^2) ). Cf. A000122. - Peter Bala, Dec 23 2021

A261451 Expansion of Product_{k>=1} ((1+x^k)/(1-x^k))^(k+1).

Original entry on oeis.org

1, 4, 14, 44, 124, 328, 824, 1980, 4590, 10320, 22584, 48268, 101016, 207432, 418704, 832032, 1629764, 3150280, 6014998, 11354084, 21204488, 39206168, 71811256, 130369900, 234704360, 419195412, 743085912, 1307823672, 2286094704, 3970174648, 6852048368

Offset: 0

Vaclav Kotesovec, Aug 19 2015

nonn

Convolution of A005380 and A219555.

Vaclav Kotesovec, Table of n, a(n) for n = 0..1000

Cf. A156616, A005309, A261386, A261452, A261389.

nmax = 40; CoefficientList[Series[Product[((1+x^k)/(1-x^k))^(k+1), {k, 1, nmax}], {x, 0, nmax}], x]

a(n) ~ (7*Zeta(3))^(13/36) * exp(1/12 - Pi^4/(336*Zeta(3)) + Pi^2 * n^(1/3) / (2^(5/3) * (7*Zeta(3))^(1/3)) + 3/2 * ((7*Zeta(3))/2)^(1/3) * n^(2/3)) / (A * 2^(35/18) * 3^(1/2) * Pi * n^(31/36)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant.

A261647 Expansion of Product_{k>=0} ((1+x^(2k+1))/(1-x^(2k+1)))^3.

Original entry on oeis.org

1, 6, 18, 44, 102, 216, 428, 816, 1494, 2650, 4584, 7740, 12804, 20808, 33264, 52400, 81462, 125100, 189966, 285516, 425016, 627040, 917436, 1331856, 1919332, 2746926, 3905784, 5519352, 7754064, 10833192, 15055216, 20817600, 28647414, 39241336, 53517060

Offset: 0

Vaclav Kotesovec, Aug 28 2015

nonn

Vaclav Kotesovec, A method of finding the asymptotics of q-series based on the convolution of generating functions, arXiv:1509.08708 [math.CO], Sep 30 2015, p. 11.

Cf. A015128, A156616.
Cf. A080054, A007096, A014969, A261648, A014970, A014972, A103261.
Cf. A261610, A261649, A261651.
Cf. A261611, A261650, A261652.

nmax=60; CoefficientList[Series[Product[((1+x^(2*k+1))/(1-x^(2*k+1)))^3,{k,0,nmax}],{x,0,nmax}],x]

a(n) ~ exp(Pi*sqrt(3*n/2)) * 3^(1/4) / (8 * 2^(1/4) * n^(3/4)).

A285458 Expansion of Product_{k>=1} ((1 + x^k) / (1 - x^(4*k)))^k.

Original entry on oeis.org

1, 1, 2, 5, 9, 17, 30, 54, 94, 161, 269, 449, 740, 1200, 1930, 3083, 4877, 7650, 11919, 18444, 28363, 43341, 65848, 99523, 149654, 223901, 333448, 494427, 729996, 1073408, 1572264, 2294389, 3336191, 4834261, 6981727, 10050944, 14424665, 20639641, 29447118

Offset: 0

Vaclav Kotesovec, Apr 19 2017

nonn

Vaclav Kotesovec, Table of n, a(n) for n = 0..1000

Cf. A015128, A000041, A285445, A006950.

Cf. A156616, A000219, A285446, A285459.

nmax = 40; CoefficientList[Series[Product[((1+x^k)/(1-x^(4*k)))^k, {k, 1, nmax}], {x, 0, nmax}], x]

a(n) ~ exp(1/12 + 3 * (13*Zeta(3))^(1/3) * n^(2/3) / 4) * (13*Zeta(3))^(7/36) / (2 * A * sqrt(3*Pi) * n^(25/36)), where A is the Glaisher-Kinkelin constant A074962.

A285459 Expansion of Product_{k>=1} ((1 + x^k) / (1 - x^(5*k)))^k.

Original entry on oeis.org

1, 1, 2, 5, 8, 17, 29, 51, 88, 150, 254, 416, 682, 1102, 1765, 2810, 4415, 6897, 10704, 16482, 25251, 38410, 58120, 87480, 130999, 195253, 289612, 427757, 629128, 921590, 1344904, 1955246, 2832608, 4089696, 5885169, 8442269, 12073072, 17214535, 24475417

Offset: 0

Vaclav Kotesovec, Apr 19 2017

nonn

In general, if m >= 1 and g.f. = Product_{k>=1} ((1 + x^k) / (1 - x^(m*k)))^k, then a(n, m) ~ exp(1/12 + 3 * 2^(-4/3) * (3 + 4/m^2)^(1/3) * Zeta(3)^(1/3) * n^(2/3)) * (3 + 4/m^2)^(7/36) * m^(1/12) * Zeta(3)^(7/36) / (A * 2^(7/9) * sqrt(3*Pi) * n^(25/36)), where A is the Glaisher-Kinkelin constant A074962.

Vaclav Kotesovec, Table of n, a(n) for n = 0..1000

Cf. A156616 (m=1), A000219 (m=2), A285446 (m=3), A285458 (m=4).

nmax = 40; CoefficientList[Series[Product[((1+x^k)/(1-x^(5*k)))^k, {k, 1, nmax}], {x, 0, nmax}], x]

a(n) ~ exp(1/12 + 3 * 2^(-4/3) * 5^(-2/3) * (79*Zeta(3))^(1/3) * n^(2/3)) * (79*Zeta(3))^(7/36) / (A * 2^(7/9) * 5^(11/36) * sqrt(3*Pi) * n^(25/36)), where A is the Glaisher-Kinkelin constant A074962.

A295831 Expansion of Product_{k>=1} ((1 + x^(2k))/(1 - x^(2k-1)))^k.

Original entry on oeis.org

1, 1, 2, 4, 6, 11, 19, 30, 47, 76, 118, 181, 277, 417, 624, 929, 1367, 2001, 2913, 4210, 6056, 8665, 12328, 17466, 24640, 34600, 48395, 67442, 93625, 129520, 178588, 245429, 336252, 459324, 625613, 849762, 1151150, 1555378, 2096332, 2818630, 3780903, 5060240, 6757633, 9005106, 11975265

Offset: 0

Ilya Gutkovskiy, Nov 28 2017

nonn

Cf. A001935, A001936, A001937, A026007, A035528, A093160, A113415, A156616, A284474, A292037, A295832.

nmax = 44; CoefficientList[Series[Product[((1 + x^(2 k))/(1 - x^(2 k - 1)))^k, {k, 1, nmax}], {x, 0, nmax}], x]
nmax = 44; CoefficientList[Series[Exp[Sum[x^k (1 - (-1)^k x^k)/(k (1 - x^(2 k))^2), {k, 1, nmax}]], {x, 0, nmax}], x]

G.f.: Product_{k>=1} ((1 + x^(2*k))/(1 - x^(2*k-1)))^k.
G.f.: exp(Sum_{k>=1} x^k*(1 - (-1)^k*x^k)/(k*(1 - x^(2*k))^2)).
a(n) ~ exp(3*(7*Zeta(3))^(1/3) * n^(2/3) / 4 + Pi^2 * n^(1/3) / (12 * (7*Zeta(3))^(1/3)) - Pi^4 / (3024*Zeta(3)) - 1/24) * A^(1/2) * (7*Zeta(3))^(11/72) / (2^(11/8) * sqrt(3*Pi) * n^(47/72)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Nov 28 2017

A295832 Expansion of Product_{k>=1} ((1 + x^(2k-1))/(1 - x^(2k)))^k.

Original entry on oeis.org

1, 1, 1, 3, 5, 8, 12, 20, 33, 50, 74, 114, 175, 257, 375, 555, 814, 1171, 1677, 2406, 3435, 4855, 6825, 9591, 13428, 18667, 25851, 35745, 49250, 67544, 92340, 125966, 171345, 232257, 313945, 423470, 569778, 764465, 1023231, 1366827, 1821756, 2422394, 3214318, 4257088, 5627086, 7422941

Offset: 0

Ilya Gutkovskiy, Nov 28 2017

nonn

Cf. A000219, A006950, A113415, A156616, A224364, A263140, A273225, A273226, A274621, A295831.

nmax = 45; CoefficientList[Series[Product[((1 + x^(2 k - 1))/(1 - x^(2 k)))^k, {k, 1, nmax}], {x, 0, nmax}], x]
nmax = 45; CoefficientList[Series[Exp[Sum[x^k ((-1)^(k + 1) + x^k)/(k (1 - x^(2 k))^2), {k, 1, nmax}]], {x, 0, nmax}], x]

G.f.: Product_{k>=1} ((1 + x^(2*k-1))/(1 - x^(2*k)))^k.
G.f.: exp(Sum_{k>=1} x^k*((-1)^(k+1) + x^k)/(k*(1 - x^(2*k))^2)).
a(n) ~ exp(3 * (7*Zeta(3))^(1/3) * n^(2/3) / 4 + Pi^2 * n^(1/3) / (24 * (7*Zeta(3))^(1/3)) - Pi^4 / (12096 * Zeta(3)) + 1/12) * (7*Zeta(3))^(7/36) / (A * 2^(23/24) * sqrt(3*Pi) * n^(25/36)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Nov 28 2017

A306081 Expansion of e.g.f. Product_{k>=1} ((1 + (exp(x) - 1)^k) / (1 - (exp(x) - 1)^k))^k.

Original entry on oeis.org

1, 2, 14, 134, 1574, 22262, 367814, 6907574, 144942854, 3357588662, 85000841414, 2331998188214, 68862337593734, 2176283210561462, 73250933670041414, 2614843434740912054, 98632371931151518214, 3918608865052986708662, 163507638190268814991814

Offset: 0

Vaclav Kotesovec, Jun 20 2018

nonn

Convolution of A306080 and A306046.

Vaclav Kotesovec, Table of n, a(n) for n = 0..400

Cf. A156616, A305550, A306045, A306046, A306080.

nmax = 20; CoefficientList[Series[Product[((1 + (Exp[x] - 1)^k)/(1 - (Exp[x] - 1)^k))^k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]!

a(n) = Sum_{k=0..n} Stirling2(n,k) * A156616(k) * k!.

a(n) ~ n! * exp(3 * (7*Zeta(3))^(1/3) * n^(2/3) / (4 * log(2)^(2/3)) + (1 - log(2)) * (7*Zeta(3))^(2/3) * n^(1/3) / (8 * log(2)^(4/3)) - 7*(log(2)^2 + log(2) - 1) * Zeta(3) / (48 * log(2)^2) + 1/12) * (7*Zeta(3))^(7/36) / (A * 2^(13/12) * sqrt(3*Pi) * n^(25/36) * (log(2))^(n + 11/36)), where A is the Glaisher-Kinkelin constant A074962. - Vaclav Kotesovec, Jun 22 2018

A005309 Fermionic string states.

Original entry on oeis.org

1, 0, 2, 4, 8, 16, 32, 60, 114, 212, 384, 692, 1232, 2160, 3760, 6480, 11056, 18728, 31474, 52492, 86976, 143176, 234224, 380988, 616288, 991624, 1587600, 2529560, 4011808, 6334656, 9960080, 15596532, 24327122, 37801568, 58525152, 90291232, 138825416

Offset: 0

N. J. A. Sloane

nonn

See the reference for precise definition.

The g.f. -(1-2*z+2*z**2)/(-1+2*z) conjectured by Simon Plouffe in his 1992 dissertation is not correct.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Vaclav Kotesovec, Table of n, a(n) for n = 0..1000
T. Curtright, Counting symmetry patterns in the spectra of strings, in H. J. de Vega and N. Sánchez, editors, String Theory, Quantum Cosmology and Quantum Gravity. Integrable and Conformal Invariant Theories. World Scientific, Singapore, 1987, pp. 304-333, eq. (3.39) and Table 3.
Simon Plouffe, Approximations de séries génératrices et quelques conjectures, Dissertation, Université du Québec à Montréal, 1992; arXiv:0911.4975 [math.NT], 2009.
Simon Plouffe, 1031 Generating Functions, Appendix to Thesis, Montreal, 1992

Cf. A156616, A261451, A261386, A261452, A261389.

G.f. Product_{k>=1} ((1+x^k)/(1-x^k))^(k-1). - Vaclav Kotesovec, Aug 19 2015
Convolution of A052847 and A052812. - Vaclav Kotesovec, Aug 19 2015
a(n) ~ 2^(7/18) * (7*Zeta(3))^(1/36) * exp(1/12 - Pi^4/(336*Zeta(3)) - Pi^2 * n^(1/3) / (2^(5/3)*(7*Zeta(3))^(1/3)) + 3/2 * (7*Zeta(3)/2)^(1/3) * n^(2/3)) / (A * sqrt(3) * n^(19/36)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant. - Vaclav Kotesovec, Aug 19 2015

A261384 Expansion of Product_{k>=1} (1+x^k)^(2k-1) / (1-x^k)^(2k).

Original entry on oeis.org

1, 3, 12, 39, 117, 331, 893, 2307, 5766, 13986, 33046, 76302, 172567, 383013, 835731, 1795236, 3801105, 7941439, 16386777, 33423342, 67435311, 134675784, 266385932, 522135379, 1014643823, 1955656848, 3740191268, 7100290646, 13383997996, 25058666367

Offset: 0

Vaclav Kotesovec, Aug 17 2015

nonn

Convolution of A161870 and A255835.

Vaclav Kotesovec, Table of n, a(n) for n = 0..2000

Cf. A006950, A015128, A156616, A161870, A255835, A261386.

nmax = 40; CoefficientList[Series[Product[(1+x^k)^(2*k-1)/(1-x^k)^(2*k), {k, 1, nmax}], {x, 0, nmax}], x]

a(n) ~ (7*Zeta(3))^(2/9) * exp(1/6 - Pi^4/(6048*Zeta(3)) - Pi^2 * n^(1/3) / (12*(7*Zeta(3))^(1/3)) + 3/2*(7*Zeta(3))^(1/3) * n^(2/3)) / (A^2 * 2^(1/6) * sqrt(3*Pi) * n^(13/18)), where Zeta(3) = A002117 and A = A074962 is the Glaisher-Kinkelin constant.

cp's OEIS Frontend

A285675 Expansion of Product_{n>0} ((1-x^n)/(1+x^n))^n in powers of x.

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A261451 Expansion of Product_{k>=1} ((1+x^k)/(1-x^k))^(k+1).

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A261647 Expansion of Product_{k>=0} ((1+x^(2*k+1))/(1-x^(2*k+1)))^3.

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A285458 Expansion of Product_{k>=1} ((1 + x^k) / (1 - x^(4*k)))^k.

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A285459 Expansion of Product_{k>=1} ((1 + x^k) / (1 - x^(5*k)))^k.

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A295831 Expansion of Product_{k>=1} ((1 + x^(2*k))/(1 - x^(2*k-1)))^k.

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A295832 Expansion of Product_{k>=1} ((1 + x^(2*k-1))/(1 - x^(2*k)))^k.

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A306081 Expansion of e.g.f. Product_{k>=1} ((1 + (exp(x) - 1)^k) / (1 - (exp(x) - 1)^k))^k.

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A005309 Fermionic string states.

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A261647 Expansion of Product_{k>=0} ((1+x^(2k+1))/(1-x^(2k+1)))^3.

A295831 Expansion of Product_{k>=1} ((1 + x^(2k))/(1 - x^(2k-1)))^k.

A295832 Expansion of Product_{k>=1} ((1 + x^(2k-1))/(1 - x^(2k)))^k.

A261384 Expansion of Product_{k>=1} (1+x^k)^(2k-1) / (1-x^k)^(2k).