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A002509
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Expansion of a modular function for Gamma_0(14).
(Formerly M3256 N1314)
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2
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1, -1, 4, -5, 15, -19, 45, -52, 118, -137, 281, -316, 625, -695, 1331, -1444, 2696, -2907, 5308, -5640, 10122, -10650, 18845, -19628, 34241, -35378, 61036, -62524, 106783, -108593, 183799, -185646, 311625, -312800, 521232, -520044, 860728, -854151, 1404871, -1386868, 2267960, -2228161
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OFFSET
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4,3
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REFERENCES
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N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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FORMULA
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eta(z)*eta(14z)^11/(eta(2z)^5*eta(7z)^7)
Euler transform of period 14 sequence [ -1, 4, -1, 4, -1, 4, 6, 4, -1, 4, -1, 4, -1, 0, ...]. - Michael Somos, Nov 10 2005
a(2*n) - a(2*n-1) ~ exp(4*Pi*sqrt(n/7)) / (sqrt(2) * 7^(9/4) * n^(3/4)). - Vaclav Kotesovec, Apr 09 2018
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MATHEMATICA
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QP = QPochhammer; A = x*O[x]^50; s = QP[x+A]*(QP[x^14+A]^11/QP[x^2+A]^5/ QP[x^7+A]^7); CoefficientList[s, x] (* Jean-François Alcover, Nov 29 2015, adapted from PARI *)
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PROG
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(PARI) {a(n)=local(A); if(n<4, 0, n-=4; A=x*O(x^n); polcoeff( eta(x+A)*eta(x^14+A)^11/ eta(x^2+A)^5/eta(x^7+A)^7, n))} /* Michael Somos, Nov 10 2005 */
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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EXTENSIONS
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More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jan 14 2001
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STATUS
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approved
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