A073773 - OEIS

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A073773

Number of plane binary trees of size n+2 and height n.

0, 0, 0, 6, 40, 152, 480, 1376, 3712, 9600, 24064, 58880, 141312, 333824, 778240, 1794048, 4096000, 9273344, 20840448, 46530560, 103284736, 228065280, 501219328, 1096810496, 2390753280, 5192548352, 11240734720, 24259854336 (list; graph; refs; listen; history; internal format)

	OFFSET	`0,4`
	LINKS	`H. Bottomley & A. Karttunen Derivations of the formulae for the diagonals of A073345 & A073346.`
	FORMULA	`a(n < 3) = 0, a(n) = ((n^2 - 6)*2^(n-2))`
	EXAMPLE	`a(3) = 6 because there exists only these six binary trees of size 5 and height 3:` `_\/\/_______\/\/_\/_\/_____\/_\/_\/___\/___V_V___` `__\/_\/___\/_\/___\/_\/___\/_\/___\/_\/___\/_\/__` `___\./_____\./_____\./_____\./_____\./_____\./___`
	MAPLE	A073773 := n -> `if`((n < 3), 0, ((n^2 - 6)*2^(n-2)));
	CROSSREFS	`A073773(n) = A073345(n+2, n). Cf. A014480, A073774, A028878.` `Sequence in context: A002595 A089207 A027777 * A001919 A005553 A055344` `Adjacent sequences: A073770 A073771 A073772 * A073774 A073775 A073776`
	KEYWORD	`nonn`
	AUTHOR	`Antti Karttunen Aug 11 2002`

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Last modified February 15 12:21 EST 2012. Contains 205785 sequences.