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A033690
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Theta series of A2[ hole ]^4.
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4
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1, 4, 14, 28, 57, 84, 148, 196, 312, 364, 546, 624, 910, 988, 1352, 1456, 1974, 2072, 2710, 2800, 3705, 3724, 4816, 4788, 6188, 6076, 7658, 7644, 9620, 9352, 11536, 11284, 14183, 13468, 16542, 15996, 19864, 18928, 22820, 21904, 26880, 25284
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OFFSET
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0,2
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REFERENCES
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J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 111, Eq (63)^4.
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LINKS
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Table of n, a(n) for n=0..41.
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FORMULA
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Expansion of q^(-4/3) * (eta(q^3)^3 / eta(q))^4 in powers of q. - Michael Somos Aug 22 2007
Expansion of c(q)^4 / (81 * q^(4/3)) in powers of q where c() is a cubic AGM function. - Michael Somos Aug 22 2007
Euler transform of period 3 sequence [ 4, 4, -8, ...]. - Michael Somos Aug 22 2007
A092342(n) = A000731(n) + 81*a(n-1). - Michael Somos Aug 22 2007
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EXAMPLE
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q^4 + 4*q^7 + 14*q^10 + 28*q^13 + 57*q^16 + 84*q^19 + 148*q^22 + ...
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PROG
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(PARI) {a(n) = local(A); if(n<0, 0, A = x*O(x^n); polcoeff( (eta(x^3 +A)^3 / eta(x +A) )^4, n))} /* Michael Somos Aug 22 2007 */
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CROSSREFS
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A033685^4.
Sequence in context: A200546 A066907 A130439 * A103779 A049451 A079776
Adjacent sequences: A033687 A033688 A033689 * A033691 A033692 A033693
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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