login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A003228 Endpoints in trees with n nodes.
(Formerly M0351)
6
1, 2, 2, 5, 9, 21, 43, 101, 226, 556, 1333, 3365, 8500, 22007, 57258, 151264, 401761, 1077063, 2902599, 7871250, 21440642, 58672589, 161155637, 444240627, 1228400744, 3406668865, 9472308269, 26402207803, 73755064178 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
R. W. Robinson and A. J. Schwenk, The distribution of trees in a large random tree, Discr. Math., 12 (1975), 359-372.
Eric Weisstein's World of Mathematics, Tree Leaf.
FORMULA
a(n) = Sum_{k=1..n} k*c(n, k), where c(n, k) = A055290(n, k) has g.f. (1-x+x*y)*B(x, y)+(1/2)*(B(x^2, y^2)-B(x, y)^2) and B(x, y) is g.f. for A055372.
CROSSREFS
Sequence in context: A002990 A060405 A326493 * A184713 A110182 A309867
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected and extended with formula by Christian G. Bower, May 25 2000
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)