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A305204
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Expansion of Product_{k>=1} 1/(1 - (k*(k + 1)/2)*x^k).
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2
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1, 1, 4, 10, 29, 62, 176, 363, 931, 2029, 4751, 10062, 23749, 48959, 109342, 230981, 500344, 1031667, 2223218, 4531585, 9570395, 19523510, 40411313, 81628389, 168484616, 336850254, 685112670, 1369559157, 2757908932, 5464925114, 10958578421, 21574592680
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f.: Product_{k>=1} 1/(1 - A000217(k)*x^k).
G.f.: exp(Sum_{k>=1} Sum_{j>=1} (j*(j + 1))^k*x^(j*k)/(k*2^k)).
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MAPLE
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b:= proc(n, i) option remember; `if`(n=0 or i=1,
1, b(n, i-1)+(1+i)*i/2*b(n-i, min(n-i, i)))
end:
a:= n-> b(n$2):
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MATHEMATICA
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nmax = 31; CoefficientList[Series[Product[1/(1 - (k (k + 1)/2) x^k), {k, 1, nmax}], {x, 0, nmax}], x]
nmax = 31; CoefficientList[Series[Exp[Sum[Sum[(j (j + 1))^k x^(j k)/(k 2^k), {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d^(k/d + 1) ((d + 1)/2)^(k/d), {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 31}]
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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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