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A182032
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Expansion of eta(q^2)^3 * eta(q^9) * eta(q^12)^4 / (eta(q) * eta(q^4)^2 * eta(q^6)^2 * eta(q^18) * eta(q^36)^2) in powers of q.
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7
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1, 1, -1, 0, 1, 0, 1, 1, 0, 0, -1, 0, 1, -1, 0, 0, 0, 0, -1, 1, 0, 0, 2, 0, -1, 0, 0, 0, -2, 0, 0, -3, 0, 0, -1, 0, 1, 4, 0, 0, 4, 0, 2, 1, 0, 0, -4, 0, 0, -6, 0, 0, -1, 0, -2, 5, 0, 0, 8, 0, -3, 1, 0, 0, -8, 0, -1, -10, 0, 0, -2, 0, 4, 11, 0, 0, 14, 0, 4, 4, 0, 0, -14, 0, 1, -19, 0, 0, -4, 0, -4, 17, 0, 0, 24, 0, -6, 4, 0, 0, -23, 0
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OFFSET
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-2,23
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COMMENTS
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LINKS
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FORMULA
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Expansion of q^(-2) * chi(q) * chi(-q^2) * psi(q^6)^2 / (psi(q^9) * psi(q^18)) in powers of q where psi(), chi() are Ramanujan theta functions.
Euler transform of period 36 sequence [ 1, -2, 1, 0, 1, 0, 1, 0, 0, -2, 1, -2, 1, -2, 1, 0, 1, 0, 1, 0, 1, -2, 1, -2, 1, -2, 0, 0, 1, 0, 1, 0, 1, -2, 1, 0, ...].
a(6*n) = 0 unless n=0. a(6*n + 1) = a(6*n + 3) = 0.
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EXAMPLE
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q^-2 + q^-1 - 1 + q^2 + q^4 + q^5 - q^8 + q^10 - q^11 - q^16 + q^17 + ...
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MATHEMATICA
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QP = QPochhammer; s = QP[q^2]^3*QP[q^9]*(QP[q^12]^4 / (QP[q]*QP[q^4]^2* QP[q^6]^2*QP[q^18]*QP[q^36]^2)) + O[q]^90; CoefficientList[s, q] (* Jean-François Alcover, Nov 24 2015 *)
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PROG
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(PARI) {a(n) = local(A); if( n<-2, 0, n+=2; A = x * O(x^n); polcoeff( eta(x^2 + A)^3 * eta(x^9 + A) * eta(x^12 + A)^4 / (eta(x + A) * eta(x^4 + A)^2 * eta(x^6 + A)^2 * eta(x^18 + A) * eta(x^36 + A)^2), n))}
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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