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A121444
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Expansion of q^(-5/12)eta(q^2)eta(q^3)eta(q^6)/eta(q) in powers of q.
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7
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1, 1, 1, 1, 1, 2, 0, 1, 1, 1, 2, 1, 1, 0, 1, 2, 1, 0, 2, 1, 1, 1, 1, 1, 1, 2, 1, 0, 0, 1, 2, 2, 1, 1, 0, 3, 0, 1, 1, 0, 2, 0, 1, 1, 2, 2, 1, 1, 0, 1, 1, 1, 2, 1, 1, 0, 1, 2, 1, 0, 3, 0, 0, 1, 1, 2, 1, 1, 1, 1, 3, 1, 0, 1, 0, 2, 0, 1, 1, 1, 2, 1, 0, 0, 1, 3, 2, 1, 1, 2, 0, 1, 1, 0, 0, 2, 2, 0, 1, 1, 2, 1, 1, 2, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,6
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FORMULA
| Euler transform of period 6 sequence [ 1, 0, 0, 0, 1, -2, ...].
G.f.: Product_{k>0} (1+x^k)(1-x^(3k))(1-x^(6k)).
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PROG
| (PARI) {a(n)=local(A); if(n<0, 0, A=x*O(x^n); polcoeff( eta(x^2+A)*eta(x^3+A)*eta(x^6+A)/eta(x+A), n))}
(PARI) {a(n)=if(n<0, 0, n=12*n+5; sumdiv(n, d, (d%4==1)-(d%4==3))/2)}
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CROSSREFS
| Cf. A098098 is convolution of a(n) with itself.
A121363(3n+1)=-2*a(n).
Sequence in context: A053692 A099494 A030341 * A118230 A179181 A153246
Adjacent sequences: A121441 A121442 A121443 * A121445 A121446 A121447
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KEYWORD
| nonn
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AUTHOR
| Michael Somos, Jul 30 2006
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