id:A124973 - OEIS Search Results

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a(n) = Sum_{0 <= k < n/2} a(k)a(n-1-k), with a(0) = a(1) = 1.

+0
2

1, 1, 1, 1, 2, 3, 6, 11, 22, 42, 87, 174, 365, 745, 1587, 3303, 7103, 14974, 32477, 69284, 151172, 325077, 713400, 1545719, 3406989, 7423648, 16429555, 35992438, 79912474, 175785514, 391488688, 864591621, 1930333822, 4276537000 (list; graph; listen)

	OFFSET	`0,5`
	COMMENT	`Number of unordered rooted trees with all outdegrees <= 2 and, if a node has two subtrees, they have a different number of nodes (equivalently, ordered rooted trees where the left subtree has more nodes than the right subtree).`
	CROSSREFS	`Cf. A000992, A001190, A032305, A000108.` `Sequence in context: A141072 A043328 A002083 this_sequence A043327 A005578 A058050` `Adjacent sequences: A124970 A124971 A124972 this_sequence A124974 A124975 A124976`
	KEYWORD	`easy,nonn`
	AUTHOR	`Franklin T. Adams-Watters (FrankTAW(AT)Netscape.net), Nov 14 2006`

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Last modified November 24 14:25 EST 2009. Contains 167438 sequences.

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