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A100101
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Bell(2n)*(2n-1)!!, where Bell are the Bell numbers A000110.
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0
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1, 2, 45, 3045, 434700, 109596375, 43800340815, 25797179878470, 21243510135522675, 23503974546075598575, 33865310276598741840900, 61964234361152712204340725, 141027420945032510510113517025
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OFFSET
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0,2
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COMMENTS
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This sequence arises in the normal ordering problem the exponential of square of boson number operator.
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LINKS
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FORMULA
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E.g.f.: G(x) = Sum_{k>=0} exp((k*x)^2/2-1)/k!; a(n) = subs(x=0, (d^(2n)/dx^(2n))G(x)).
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MATHEMATICA
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PROG
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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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