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A305406
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Expansion of Sum_{k>=0} binomial(2*k,k)*x^k/Product_{j=1..k} (1 - j*x).
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3
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1, 2, 8, 40, 234, 1544, 11242, 89016, 758504, 6900012, 66590782, 678322704, 7262393832, 81431657220, 953339019606, 11622207372104, 147199295291518, 1932876310310488, 26265519359529974, 368752956750812256, 5340795881536757632, 79691179458925839676, 1223524383429928039306
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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E.g.f.: exp(2*(exp(x) - 1))*BesselI(0,2*(exp(x) - 1)).
a(n) = Sum_{k=0..n} Stirling2(n,k)*binomial(2*k,k).
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MAPLE
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b:= proc(n, m) option remember;
`if`(n=0, binomial(2*m, m), m*b(n-1, m)+b(n-1, m+1))
end:
a:= n-> b(n, 0):
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MATHEMATICA
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nmax = 22; CoefficientList[Series[Sum[Binomial[2 k, k] x^k/Product[1 - j x, {j, 1, k}], {k, 0, nmax}], {x, 0, nmax}], x]
nmax = 22; CoefficientList[Series[Exp[2 (Exp[x] - 1)] BesselI[0, 2 (Exp[x] - 1)], {x, 0, nmax}], x] Range[0, nmax]!
Table[Sum[StirlingS2[n, k] Binomial[2 k, k], {k, 0, n}], {n, 0, 22}]
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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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