This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A220830 #17 Dec 15 2020 12:52:25 %S A220830 0,0,1,6,30,140,663,3186,15642,78441,400842,2084698,11009358,58955139, %T A220830 319619706,1752122667,9700923252,54194387085,305216395077, %U A220830 1731579241287,9889280682948,56822058078669,328300135291659,1906449141877331,11122447670117451,65168427936552522 %N A220830 Number of unrooted binary leaf-multi-labeled trees with n leaves on the label set [3], with each label used at least once. %H A220830 Andrew Howroyd, <a href="/A220830/b220830.txt">Table of n, a(n) for n = 1..200</a> %H A220830 V. P. Johnson, <a href="https://people.math.sc.edu/czabarka/Theses/JohnsonThesis.pdf">Enumeration Results on Leaf Labeled Trees</a>, Ph. D. Dissertation, Univ. Southern Calif., 2012. %F A220830 a(n) = A220827(n) - 3*A220826(n) + 3*A129860(n). - _Andrew Howroyd_, Dec 14 2020 %Y A220830 Column 3 of A339650. %Y A220830 Cf. A129860, A220826, A220827, A220829. %K A220830 nonn %O A220830 1,4 %A A220830 _N. J. A. Sloane_, Dec 22 2012 %E A220830 Terms a(11) and beyond from _Andrew Howroyd_, Dec 14 2020