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A208831
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G.f.: 1/(1-x) = Sum_{n>=0} a(n) * x^n / Product_{k=1..2*n} (1 + k*x).
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1
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1, 1, 4, 34, 470, 9246, 239254, 7735818, 301515326, 13798284326, 726653380406, 43347208596090, 2892081998352630, 213573932091190350, 17305963353368021974, 1527409032389494461130, 145910774659458343922094, 15004445714376212721001782, 1653029709428208769065420054
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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)*(1+2*x)) + 4*x^2/((1+x)*(1+2*x)*(1+3*x)*(1+4*x)) + 34*x^3/((1+x)*(1+2*x)*(1+3*x)*(1+4*x)*(1+5*x)*(1+6*x)) + 470*x^4/((1+x)*(1+2*x)*(1+3*x)*(1+4*x)*(1+5*x)*(1+6*x)*(1+7*x)*(1+8*x)) +...
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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, 2*k, (1+j*x+x*O(x^n)) )), n))}
for(n=0, 20, 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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