id:A119367 - OEIS Search Results

Search: id:A119367

Displaying 1-1 of 1 results found.

page 1

A119367

Number of rooted planar n-trees whose number of leaves is equal to 2 modulo 3.

+0
3

0, 0, 1, 3, 6, 11, 30, 126, 519, 1836, 5877, 18866, 65472, 242463, 905425, 3307371, 11889414, 42930441, 157641714, 586908936, 2194106568, 8189323686, 30541703733, 114219616809, 429214875498, 1619584557885, 6125465491551 (list; graph; listen)

	OFFSET	`0,4`
	COMMENT	`a(n)+A119365(n)+A119366(n)=A000108(n).`
	FORMULA	`a(n)=sum{k=0..n, if(mod(n-k,3)=2, (1/n)C(n,k)C(n,k+1), 0)}.`
	CROSSREFS	`Sequence in context: A109781 A101958 A153982 this_sequence A079801 A119104 A102253` `Adjacent sequences: A119364 A119365 A119366 this_sequence A119368 A119369 A119370`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paul Barry (pbarry(AT)wit.ie), May 16 2006`

page 1

Search completed in 0.003 seconds

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

AT&T Labs Research