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Search: id:A073075
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| A073075 |
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Generating function satisfies A(x) = exp(2A(x)x + 2A(x^3)x^3/3 + 2A(x^5)x^5/5 + 2A(x^7)x^7/7 +...). |
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+0
1
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| 1, 2, 6, 22, 86, 358, 1554, 6950, 31822, 148434, 702802, 3369046, 16319050, 79749294, 392711090, 1946732854, 9706813790, 48651303118, 244972282734, 1238621756174, 6286144819506, 32011282859598, 163517409895602
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f.: A(x) = exp(sum_{n=0..inf} 2A(x^(2n+1))*x^(2n+1)/(2n+1)), A(0)=1, where A(x) = 1 + 2x + 6x^2 + 22x^3 + 86x^4 + 358x^5 +...
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MAPLE
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spec := [S, {B=Set(S), C=PowerSet(S), S=Prod(Z, B, C)}, unlabeled]: seq(combstruct[count](spec, size=n), n=1..20); (Vladeta Jovovic (vladeta(AT)Eunet.yu), Feb 10 2005)
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CROSSREFS
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Adjacent sequences: A073072 A073073 A073074 this_sequence A073076 A073077 A073078
Sequence in context: A107247 A047849 A107245 this_sequence A101043 A101046 A032351
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KEYWORD
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easy,nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Aug 17 2002
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