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Search: id:A052855
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| A052855 |
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Number of forests of rooted trees of nonempty sets with n points. (Each node is a set of 1 or more points.) |
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+0
1
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| 1, 1, 3, 8, 24, 71, 224, 710, 2318, 7659, 25703, 87153, 298574, 1031104, 3587263, 12558652, 44214807, 156438309, 555973965, 1983817178, 7104313970, 25525304569, 91986529421, 332408847422, 1204259931815, 4373027942634
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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Euler transform of A036249 (as well as first differences thereof). - Frank Adams-Watters (FrankTAW(AT)Netscape.net), Feb 08 2006
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LINKS
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INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 823
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MAPLE
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spec := [S, {B=Sequence(Z, 1 <= card), S=Set(C), C=Prod(B, S)}, unlabeled]: seq(combstruct[count](spec, size=n), n=0..20);
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CROSSREFS
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First differences of A036249 and A029856.
Sequence in context: A079121 A027077 A153774 this_sequence A133787 A080923 A118264
Adjacent sequences: A052852 A052853 A052854 this_sequence A052856 A052857 A052858
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KEYWORD
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easy,nonn
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AUTHOR
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encyclopedia(AT)pommard.inria.fr, Jan 25 2000
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EXTENSIONS
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More terms from Frank Adams-Watters (FrankTAW(AT)Netscape.net), Feb 08 2006
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