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A124382
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O.g.f.: A(x) = Sum_{n>=0} x^n*Product_{k=0..n} (1 + k*(k+1)*(k+2)/6*x).
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0
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1, 1, 2, 6, 20, 90, 465, 2826, 20020, 158348, 1430189, 14217275, 157279196, 1903617880, 25151383277, 361228405394, 5594555181227, 93472423847492, 1671138501448565, 31988293954710201, 651665490924639449
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OFFSET
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0,3
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LINKS
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EXAMPLE
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A(x) = 1 + x*(1+x) + x^2*(1+x)*(1+4x) + x^3*(1+x)*(1+4x)*(1+10x) +...
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PROG
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(PARI) a(n)=polcoeff(sum(k=0, n, x^k*prod(j=0, k, 1+j*(j+1)*(j+2)/3!*x+x*O(x^n))), 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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