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Search: id:A121667
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| A121667 |
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Expansion of (eta(q)eta(q^2)/(eta(q^3)eta(q^6)))^4 in powers of q. |
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+0
1
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| 1, -4, -2, 28, -27, -52, 136, -108, -162, 620, -486, -760, 1970, -1404, -1940, 6048, -4293, -6100, 15796, -10692, -14264, 40232, -27108, -36496, 93285, -61020, -79054, 211624, -137781, -179296, 451680, -288360, -365780, 945836, -601020, -763016, 1897294, -1188756
(list; graph; listen)
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OFFSET
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-1,2
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FORMULA
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Expansion of 9*b(q)*b(q^2)/(c(q)*c(q^2)) in powers of q where b(q),c(q) are cubic AGM analog functions.
Euler transform of period 6 sequence [ -4, -8, 0, -8, -4, 0, ...].
G.f. A(x) satisfies 0=f(A(x), A(x^2)) where f(u,v)=(u^2+u*v+v^2)^2 -u*v*(9+u+v)*(u*v+9*(u+v)).
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PROGRAM
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(PARI) {a(n)=if(n<-1, 0, n++; A=x*O(x^n); polcoeff( (eta(x+A)*eta(x^2+A)/eta(x^3+A)/eta(x^6+A))^4, n))}
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CROSSREFS
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Cf. A045487, A007257.
Sequence in context: A140331 A095896 A123670 this_sequence A093991 A030447 A076936
Adjacent sequences: A121664 A121665 A121666 this_sequence A121668 A121669 A121670
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KEYWORD
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sign
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AUTHOR
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Michael Somos, Aug 14 2006
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