A220827 Number of unrooted binary leaf-multi-labeled trees with n leaves on the label set [3].

3, 6, 10, 21, 63, 227, 891, 3876, 17790, 85536, 424926, 2169376, 11312838, 60065901, 323746095, 1767667332, 9760149468, 54422364834, 306101712771, 1735044593418, 9902940693084, 56876247586827, 328516343529525, 1907316302027081, 11125942281844011, 65182572852807465

Offset: 1

Author

N. J. A. Sloane, Dec 22 2012

Keywords

• nonn

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 3 of A339649.

Extensions

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