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A209405
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G.f.: 1/(1-x) = Sum_{n>=0} a(n)*x^n*Product_{k=1..n+1} (1-x^k).
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1
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1, 2, 3, 6, 8, 15, 21, 34, 47, 74, 99, 151, 201, 287, 383, 540, 701, 970, 1255, 1688, 2171, 2882, 3657, 4801, 6058, 7819, 9816, 12566, 15619, 19826, 24540, 30812, 37950, 47319, 57901, 71769, 87435, 107525, 130482, 159660, 192721, 234633, 282240, 341656, 409549
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OFFSET
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0,2
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LINKS
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EXAMPLE
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G.f.: 1/(1-x) = 1*(1-x) + 2*x*(1-x)*(1-x^2) + 3*x^2*(1-x)*(1-x^2)*(1-x^3) + 6*x^3*(1-x)*(1-x^2)*(1-x^3)*(1-x^4) + 8*x^4*(1-x)*(1-x^2)*(1-x^3)*(1-x^4)*(1-x^5) +...
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PROG
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(PARI) {a(n)=local(A=[1]); for(i=1, n+1, A=concat(A, 0); A[#A]=1-polcoeff(sum(m=1, #A, A[m]*x^m*prod(k=1, m, 1-x^k +x*O(x^#A) )), #A) ); A[n+1]}
for(n=0, 50, print1(a(n), ", "))
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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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