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Search: id:A054274
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| A054274 |
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G.f.: Product_{n=1..inf} (1-x^n)*(1-x^(5*n))/(1-x^(3*n))^2. |
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+0
1
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| 1, -1, -1, 2, -2, -2, 6, -3, -5, 12, -8, -9, 24, -14, -18, 42, -26, -31, 76, -45, -54, 126, -76, -88, 210, -121, -144, 332, -196, -225, 526, -302, -351, 804, -464, -531, 1224, -698, -800, 1818, -1040, -1179, 2688, -1519, -1728, 3902, -2212, -2491, 5632, -3167, -3571, 8016, -4508
(list; graph; listen)
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OFFSET
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0,4
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LINKS
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A. J. Guttmann, Indicators of solvability for lattice models, Discrete Math., 217 (2000), 167-189.
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FORMULA
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Euler transform of period 15 sequence [ -1, -1, 1, -1, -2, 1, -1, -1, 1, -2, -1, 1, -1, -1, 0, ...]. - Michael Somos Sep 21 2005
Expansion of eta(q)eta(q^5)/eta(q^3)^2 in powers of q. - Michael Somos Sep 21 2005
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EXAMPLE
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1 -q -q^2 +2*q^3 -2*q^4 -2*q^5 +6*q^6 -3*q^7 -5*q^8 +12*q^9 +...
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PROGRAM
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(PARI) {a(n)=local(A); if(n<0, 0, A=x*O(x^n); polcoeff( eta(x+A)*eta(x^5+A)/eta(x^3+A)^2, n))} /* Michael Somos Sep 21 2005 */
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CROSSREFS
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Sequence in context: A081668 A126615 A158524 this_sequence A053695 A119918 A084867
Adjacent sequences: A054271 A054272 A054273 this_sequence A054275 A054276 A054277
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KEYWORD
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sign
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), May 08 2000
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