|
| |
|
|
A047864
|
|
Number of labeled bipartite graphs with n nodes.
|
|
9
|
|
|
|
1, 1, 2, 7, 41, 376, 5177, 103237, 2922446, 116011231, 6433447397, 498234407452, 54007795331921, 8213123246906761, 1756336596363006842, 528975889250504033527, 224688018516023267969441, 134708289561117007261966816
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
0,3
|
|
|
REFERENCES
|
H. S. Wilf, Generatingfunctionology, Academic Press, NY, 1990, p. 80, Eq. 3.11.5.
|
|
|
LINKS
|
T. D. Noe, Table of n, a(n) for n=0..50
H. S. Wilf, Generatingfunctionology, 2nd edn., Academic Press, NY, 1994, p. 89, Eq. 3.11.5.
Eric Weisstein's World of Mathematics, n-Colorable Graph
S. R. Finch, Bipartite, k-colorable and k-colored graphs
|
|
|
FORMULA
|
E.g.f. = sqrt( e.g.f. for A047863 ).
|
|
|
MATHEMATICA
|
nn = 20; a = Sum[Sum[Binomial[n, k] 2^(k (n - k)), {k, 0, n}] x^n/n!, {n, 0, nn}]; Range[0, nn]! CoefficientList[Series[a^(1/2), {x, 0, nn}], x] (* Geoffrey Critzer, Jan 15 2012 *)
|
|
|
CROSSREFS
|
Sequence in context: A101390 A113144 A006846 * A173916 A163921 A213434
Adjacent sequences: A047861 A047862 A047863 * A047865 A047866 A047867
|
|
|
KEYWORD
|
nonn,nice,easy
|
|
|
AUTHOR
|
N. J. A. Sloane.
|
|
|
STATUS
|
approved
|
| |
|
|
