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A200793
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The number of forests on n nodes of rooted labeled binary trees (each node has degree <=2).
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0
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1, 1, 3, 16, 121, 1191, 14461, 209098, 3510921, 67175461, 1443249271, 34412298636, 901898694313, 25775139581491, 797824620178041, 26592701386533766, 949705032131053201, 36181186751341438473, 1464760631695118359051, 62798619981256526628136
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OFFSET
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0,3
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LINKS
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FORMULA
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E.g.f.: exp(A(x)) where A(x) is the e.g.f. for A036774.
a(n) ~ sqrt(2-sqrt(2)) * (1+sqrt(2))^(n+1) * exp(sqrt(2)-n) * n^(n-1). - Vaclav Kotesovec, Sep 25 2013
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MATHEMATICA
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u=(1-x-((x-1)^2-2x^2)^(1/2))/x; Range[0, 20]! CoefficientList[Series[Exp[u], {x, 0, 20}], x]
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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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