A108091
Coefficients of series whose 8th power is the theta series of E_8 (see A004009).
Original entry on oeis.org
1, 30, -2880, 416640, -69178110, 12378401280, -2321610157440, 449733567736320, -89200812128140800, 18013245273252679710, -3689479088922151082880, 764375901202388789804160, -159862757100127037505991680, 33699694000689939789618455040, -7152050326608893289997995966720, 1526705794390267864554876727856640
Offset: 0
More precisely, the theta series of E_8 begins 1 + 240*q^2 + 2160*q^4 + 6720*q^6 + 17520*q^8 + ... and the 8th root of this is 1 + 30*q^2 - 2880*q^4 + 416640*q^6 - 69178110*q^8 + ...
- N. J. A. Sloane, Seven Staggering Sequences, in Homage to a Pied Puzzler, E. Pegg Jr., A. H. Schoen and T. Rodgers (editors), A. K. Peters, Wellesley, MA, 2009, pp. 93-110.
- Seiichi Manyama, Table of n, a(n) for n = 0..424
- N. Heninger, E. M. Rains and N. J. A. Sloane, On the Integrality of n-th Roots of Generating Functions, arXiv:math/0509316 [math.NT], 2005-2006.
- N. Heninger, E. M. Rains and N. J. A. Sloane, On the Integrality of n-th Roots of Generating Functions, J. Combinatorial Theory, Series A, 113 (2006), 1732-1745.
- N. J. A. Sloane, Seven Staggering Sequences.
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nmax = 20; s = 8; CoefficientList[Series[(1 - 2*s/BernoulliB[s] * Sum[DivisorSigma[s - 1, k]*x^k, {k, 1, nmax}])^(1/16), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 02 2017 *)
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R. = PowerSeriesRing(ZZ,20)
a = R(eisenstein_series_qexp(4,20, normalization='integral'))
list(a.sqrt().sqrt().sqrt()) # Andy Huchala, Jul 10 2021
A289292
Coefficients in expansion of E_4^(1/2).
Original entry on oeis.org
1, 120, -6120, 737760, -107249640, 17385063120, -3014720249760, 547287510713280, -102701836021530600, 19762301660609250840, -3878226140959368843120, 773209219953012480001440, -156173318001506652330786720, 31888935085481430265623676560
Offset: 0
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terms = 14;
E4[x_] = 1 + 240*Sum[k^3*x^k/(1 - x^k), {k, 1, terms}];
E4[x]^(1/2) + O[x]^terms // CoefficientList[#, x]& (* Jean-François Alcover, Feb 23 2018 *)
A289392
Coefficients in expansion of E_2^(1/4).
Original entry on oeis.org
1, -6, -72, -1104, -20238, -405792, -8601840, -189317568, -4281478272, -98841343686, -2318973049008, -55118876238000, -1324194430710912, -32099173821105312, -784045854628721568, -19276683937074656064, -476644852188898489662
Offset: 0
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nmax = 20; CoefficientList[Series[(1 - 24*Sum[DivisorSigma[1, k]*x^k, {k, 1, nmax}])^(1/4), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 08 2017 *)
A092870
Expansion of Hypergeometric function F(1/12, 5/12; 1; 1728*x) in powers of x.
Original entry on oeis.org
1, 60, 39780, 38454000, 43751038500, 54538294552560, 72081445966966800, 99225259048241726400, 140744828381240373790500, 204278086466816584003782000, 301931182921413583820949947280
Offset: 0
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CoefficientList[ Series[ Hypergeometric2F1[ 1/12, 5/12, 1, 1728 x], {x, 0, 10}], x]
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{a(n) = local(an); if( n<1, n==0, an = vector(n+1); an[1] = 1; for(k=1, n, an[k+1] = an[k] * 12 * (12*k - 7) * (12*k - 11) / k^2); an[n+1])}
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{a(n)=(12^n/n!^2)*prod(k=0, n-1, (12*k+1)*(12*k+5))} \\ Paul D. Hanna, Jan 25 2011
A289308
Coefficients in expansion of E_4^(3/8).
Original entry on oeis.org
1, 90, -5940, 758520, -115431930, 19355028840, -3447208777320, 639751846440960, -122326632902618100, 23925871041887048130, -4763590542726586318440, 962102309316632909723880, -196619722885250960565506040, 40580696990507644723354537320
Offset: 0
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nmax = 20; CoefficientList[Series[(1 + 240*Sum[DivisorSigma[3,k]*x^k, {k, 1, nmax}])^(3/8), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 09 2017 *)
A289309
Coefficients in expansion of E_4^(5/8).
Original entry on oeis.org
1, 150, -5400, 625200, -86672550, 13570016400, -2289741037200, 406440122001600, -74830416797043000, 14162747887897808550, -2738995393669565720400, 538973037306449327998800, -107578899914865970323788400, 21729813219122500082762389200
Offset: 0
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nmax = 20; CoefficientList[Series[(1 + 240*Sum[DivisorSigma[3,k]*x^k, {k, 1, nmax}])^(5/8), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 08 2017 *)
A289319
Coefficients in expansion of E_4^(7/8).
Original entry on oeis.org
1, 210, -1260, 232680, -28907970, 4211355960, -671557897080, 113817372354240, -20151698294479500, 3687092782592216970, -692109989731133096760, 132609267059636375116920, -25838624519733523814390760, 5105657091664960508653858680
Offset: 0
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nmax = 20; CoefficientList[Series[(1 + 240*Sum[DivisorSigma[3,k]*x^k, {k, 1, nmax}])^(7/8), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 08 2017 *)
A289318
Coefficients in expansion of E_4^(3/4).
Original entry on oeis.org
1, 180, -3780, 447840, -59046660, 8921092680, -1463828444640, 253953515257920, -45858209756343300, 8534765953624978260, -1626301691950399586280, 315807346469727624396960, -62284193156782292089690080, 12443904711281870749228431240
Offset: 0
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nmax = 20; CoefficientList[Series[(1 + 240*Sum[DivisorSigma[3,k]*x^k, {k, 1, nmax}])^(3/4), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 08 2017 *)
A110150
G.f.: 4th root of Eisenstein series E_10 (cf. A013974).
Original entry on oeis.org
1, -66, -40392, -9009264, -3725341158, -1400292801072, -604993149612720, -262280205541007808, -118717180239835505592, -54520207050101542651506, -25525844887805197307977968, -12095360676632550886664063760, -5797006133905562955666277287792, -2803076705590018145443840156918512
Offset: 0
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nmax = 20; s = 10; CoefficientList[Series[(1 - 2*s/BernoulliB[s] * Sum[DivisorSigma[s - 1, k]*x^k, {k, 1, nmax}])^(1/4), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 02 2017 *)
A289247
Coefficients in expansion of 1/E_4^(1/8).
Original entry on oeis.org
1, -30, 3780, -616440, 111056910, -21135698280, 4165203862440, -840914061328320, 172810940671692900, -35998781800053352710, 7579904611028433074280, -1609957152292592382408360, 344417407415742189796786680, -74127324674775434904036905640
Offset: 0
E_4^(k/8):
A001943 (k=-8),
A289566 (k=-4),
A295815 (k=-2), this sequence (k=-1),
A108091 (k=1),
A289307 (k=2),
A289308 (k=3),
A289292 (k=4),
A289309 (k=5),
A289318 (k=6),
A289319 (k=7),
A004009 (k=8).
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nmax = 20; CoefficientList[Series[(1 + 240*Sum[DivisorSigma[3,k]*x^k, {k, 1, nmax}])^(-1/8), {x, 0, nmax}], x] (* Vaclav Kotesovec, Jul 09 2017 *)
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