A055540 Total number of leaves (nodes of vertex degree 1) in all graphs of n nodes.
0, 2, 4, 14, 38, 153, 766, 6259, 88064, 2324157, 116563882, 11060411527, 1968703079886, 654492092481733, 406111248305672980, 471005105043787823717, 1023566652048387537072658, 4179937690541808658135640875, 32172436158252943170541450460638
Offset: 1
Keywords
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..50
- Eric Weisstein's World of Mathematics, Tree Leaf
Programs
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PARI
\\ See A327371 for G. seq(n)=Vec(subst(deriv(G(n), y), y, 1), -n) \\ Andrew Howroyd, Jan 22 2021
Formula
a(n) = Sum_{k=1..n} k*A327371(n, k). - Andrew Howroyd, Sep 04 2019
Extensions
a(8) and a(9) from Eric W. Weisstein, Jun 02 2004
a(10) from Andrew Howroyd, Sep 04 2019
Terms a(11) and beyond from Andrew Howroyd, Jan 22 2021