A220828 Number of unrooted binary leaf-multi-labeled trees with n leaves on the label set [4].

4, 10, 20, 55, 220, 1040, 5480, 31420, 190360, 1202930, 7848720, 52543935, 359182620, 2498614620, 17640615900, 126142316865, 912047139460, 6658803466730, 49035674140240, 363881247076930, 2718918248334300, 20442286928323170, 154564065790535680, 1174669811887063830

Offset

1,1

Links

Andrew Howroyd, Table of n, a(n) for n = 1..200

V. P. Johnson, Enumeration Results on Leaf Labeled Trees, Ph. D. Dissertation, Univ. Southern Calif., 2012.

Crossrefs

Column 4 of A339649.

Sequence in context: A020149 A056412 A032275 * A015220 A047199 A038065

Adjacent sequences: A220825 A220826 A220827 * A220829 A220830 A220831

Keyword

nonn

Author

N. J. A. Sloane, Dec 22 2012

Extensions

Terms a(11) and beyond from Andrew Howroyd, Dec 14 2020

Status

approved