id:A030980 - OEIS Search Results

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Number of planted noncrossing bushes with n nodes; i.e. rooted noncrossing trees with n nodes, root degree 1 and no nonroot nodes of degree 1.

+0
2

1, 0, 3, 4, 23, 66, 280, 1030, 4207, 16852, 69747, 289950, 1222540, 5192344, 22239672, 95864902, 415730735, 1812177000, 7936353049, 34901789568, 154067755503, 682428824890, 3032173906692, 13510960371744 (list; graph; listen)

	OFFSET	`1,3`
	LINKS	`Index entries for sequences related to rooted trees`
	FORMULA	`Sum((-1)^(n-k)2^(n-k)binomial(n, k)binomial(3k-2, k-1), k=1..n)/n; G.f.: satisfies A^3 + 2 z A^3 - 2 A^2 - 4 z A^2 + A + 2 z A - z = 0`
	CROSSREFS	`Sequence in context: A042595 A002351 A042035 this_sequence A041861 A042377 A032831` `Adjacent sequences: A030977 A030978 A030979 this_sequence A030981 A030982 A030983`
	KEYWORD	`nonn`
	AUTHOR	`Emeric Deutsch (deutsch(AT)duke.poly.edu)`

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Last modified November 30 13:13 EST 2009. Contains 167758 sequences.

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