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A215529
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G.f.: 1/(1-x) = Sum_{n>=0} a(n) * x^n / Product_{k=1..n} (1 + k*x)^3.
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2
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1, 1, 4, 31, 377, 6415, 142252, 3919208, 129681162, 5025119715, 223662035160, 11260717242863, 633424125262667, 39405127536106444, 2688050940578533440, 199621706483099855304, 16038639938585081005722, 1386688821351774846453155, 128409360760837836935472512
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OFFSET
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0,3
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COMMENTS
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Compare g.f. to: 1/(1-x) = Sum_{n>=0} n!*x^n/Product_{k=1..n} (1 + k*x).
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LINKS
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EXAMPLE
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G.f.: 1/(1-x) = 1 + 1*x/(1+x)^3 + 4*x^2/((1+x)*(1+2*x))^3 + 31*x^3/((1+x)*(1+2*x)*(1+3*x))^3 + 377*x^4/((1+x)*(1+2*x)*(1+3*x)*(1+4*x))^3 +...
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PROG
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(PARI) {a(n)=if(n==0, 1, 1-polcoeff(sum(k=0, n-1, a(k)*x^k/prod(j=1, k, 1+j*x+x*O(x^n))^3), n))}
for(n=0, 25, 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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