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A265974
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Expansion of Product_{k>=1} 1/(1 - 3*k*x^k).
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4
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1, 3, 15, 54, 210, 699, 2484, 7995, 26610, 84186, 269940, 839238, 2634579, 8098194, 25032282, 76388265, 233791104, 709501596, 2157488730, 6523204836, 19747491810, 59558682132, 179762506329, 541222906812, 1630300772106, 4902697929306, 14748249476553
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OFFSET
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0,2
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LINKS
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FORMULA
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a(n) ~ c * 3^n, where c = Product_{m>=2} 1/(1 - m/3^(m-1)) = 5.86277744540963226378877460838259757442241952947887939654316926419876...
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MAPLE
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b:= proc(n, i) option remember; `if`(n=0 or i=1,
3^n, b(n, i-1) +i*3*b(n-i, min(n-i, i)))
end:
a:= n-> b(n$2):
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MATHEMATICA
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nmax=40; CoefficientList[Series[Product[1/(1-3*k*x^k), {k, 1, nmax}], {x, 0, nmax}], x]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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