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A000735
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Expansion of Product_{k>=1} (1 - x^k)^12.
(Formerly M4841 N2069)
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15
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1, -12, 54, -88, -99, 540, -418, -648, 594, 836, 1056, -4104, -209, 4104, -594, 4256, -6480, -4752, -298, 5016, 17226, -12100, -5346, -1296, -9063, -7128, 19494, 29160, -10032, -7668, -34738, 8712, -22572, 21812, 49248, -46872, 67562, 2508, -47520, -76912, -25191, 67716
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OFFSET
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0,2
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COMMENTS
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Glaisher (1905, 1907) calls this sequence {Omega(m): m=1,3,5,7,9,11,...}. - N. J. A. Sloane, Nov 24 2018
Number 9 of the 74 eta-quotients listed in Table I of Martin (1996). See g.f. B(q) below: cusp form of weight 6 and level 4.
Grosswald uses b_n where b_{2n+1} = a(n).
Cynk and Hulek on page 14 in "The Example of Ahlgren" refer to a_p of the unique normalized weight 6 level 4 cusp form. - Michael Somos, Aug 24 2012
Expansion of q^(-1/2) * k(q) * k'(q)^4 * (K(q) / (Pi/2))^6 / 4 in powers of q where k(), k'(), K() are Jacobi elliptic functions. In Glaisher 1907 denoted by Omega(m) defined in section 62 on page 37. - Michael Somos, May 19 2013
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REFERENCES
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J. W. L. Glaisher, On the representations of a number as a sum of four squares, and on some allied arithmetical functions, Quarterly Journal of Pure and Applied Mathematics, 36 (1905), 305-358. See p. 340.
Glaisher, J. W. L. (1906). The arithmetical functions P(m), Q(m), Omega(m). Quart. J. Math, 37, 36-48.
E. Grosswald, Representations of Integers as Sums of Squares. Springer-Verlag, NY, 1985, p. 121.
Newman, Morris; A table of the coefficients of the powers of eta(tau), Nederl. Akad. Wetensch. Proc. Ser. A. 59 = Indag. Math. 18 (1956), 204-216.
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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Expansion of q^(-1/2) * eta(q)^12 in powers of q.
Euler transform of period 1 sequence [-12, ...]. - Michael Somos, Sep 21 2005
Given g.f. A(x), then B(q) = q * A(q^2) satisfies 0 = f(B(q), B(q^2), B(q^4)) where f(u, v, w) = u^4*w^2 + 48*(u*v*w)^2 + 4906*u^2*w^4 - u^6. - Michael Somos, Sep 21 2005
a(n) = b(2*n + 1) where b(n) is multiplicative with b(2^e) = 0^e, b(p^e) = b(p) * b(p^(e-1)) - p^5 * b(p^(e-2)). - Michael Somos, Mar 08 2006
G.f. is a period 1 Fourier series which satisfies f(-1 / (4 t)) = 64 (t/i)^6 f(t) where q = exp(2 Pi i t). - Michael Somos, Aug 24 2012
G.f.: (Product_{k>0} (1 - x^k))^12.
G.f.: exp(-12*Sum_{k>=1} x^k/(k*(1 - x^k))). - Ilya Gutkovskiy, Feb 05 2018
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EXAMPLE
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G.f. A(x) = 1 - 12*x + 54*x^2 - 88*x^3 - 99*x^4 + 540*x^5 - 418*x^6 - 648*x^7 + ...
G.f. B(q) = q - 12*q^3 + 54*q^5 - 88*q^7 - 99*q^9 + 540*q^11 - 418*q^13 - 648*q^15 + ...
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MAPLE
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with(numtheory): etr:= proc(p) local b; b:=proc(n) option remember; local d, j; if n=0 then 1 else add(add(d*p(d), d=divisors(j)) *b(n-j), j=1..n)/n fi end end: a:= etr(n-> -12): seq(a(n), n=0..45); # Alois P. Heinz, Sep 08 2008
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MATHEMATICA
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CoefficientList[ Take[ Expand[ Product[(1 - x^k)^12, {k, 42}]], 42], x]
a[ n_] := SeriesCoefficient[ QPochhammer[ q]^12, {q, 0, n}]; (* Michael Somos, May 19 2013 *)
a[ n_] := SeriesCoefficient[ Product[ 1 - q^k, {k, n}]^12, {q, 0, n}]; (* Michael Somos, May 19 2013 *)
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PROG
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(PARI) {a(n) = if( n<0, 0, polcoeff( eta(x + x * O(x^n))^12, n))}; /* Michael Somos, Sep 21 2005 */
(Sage) CuspForms( Gamma0(4), 6, prec=85).0; # Michael Somos, May 28 2013
(Magma) Basis( CuspForms( Gamma0(4), 6), 85) [1]; /* Michael Somos, Dec 09 2013 */
(Julia) # DedekindEta is defined in A000594.
A000735List(len) = DedekindEta(len, 12)
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CROSSREFS
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A209676 is the same except for signs.
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KEYWORD
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sign,easy,nice
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AUTHOR
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STATUS
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approved
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