login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A033995 Number of bipartite graphs with n nodes. 21
1, 1, 2, 3, 7, 13, 35, 88, 303, 1119, 5479, 32303, 251135, 2527712, 33985853, 611846940, 14864650924, 488222721992, 21712049275198, 1308300679611469, 106897965189674291, 11852113048215107822, 1784730721403509209215, 365323537513403184463273 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

All bipartite graphs are perfect. - Falk Hüffner, Nov 27 2015

EULER transform of A005142 [1, 1, 1, 3, 5, 17, ...] is [1, 2, 3, 7, 13, ...]. - Michael Somos, May 13 2019

REFERENCES

R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..50

P. Erdős, D. J. Kleitman, and B. L. Rothschild, Asymptotic enumeration of k_n-free graphs. In Colloquio Internazionale sulle Teorie Combinatorie, (Rome, 1973), Tomo II, Atti dei Convegni Lincei, No. 17, pp. 19-27. Accad. Naz. Lincei, Rome.

P. Hanlon, The enumeration of bipartite graphs, Discrete Math. 28 (1979), 49-57.

S. Hougardy, Home Page

S. Hougardy, Classes of perfect graphs, Discr. Math. 306 (2006), 2529-2571.

Sage, Common Graphs (Graph Generators)

Eric Weisstein's World of Mathematics, Bipartite Graph.

Eric Weisstein's World of Mathematics, Bicolorable Graph

Eric Weisstein's World of Mathematics, n-Colorable Graph

EXAMPLE

For n=1:  o; n=2: o o, o-o; n=3: o o o, o o-o, o-o-o; n=4: o o o o, o o o-o, o-o o-o, o o-o-o, o-o-o-o, K_{2,2}, K_{3,1}. - Michael Somos, May 13 2019

CROSSREFS

Cf. A005142.

Equals A076278(n) + 1.

Sequence in context: A045611 A006840 A123408 * A013917 A293994 A196419

Adjacent sequences:  A033992 A033993 A033994 * A033996 A033997 A033998

KEYWORD

nonn,nice,changed

AUTHOR

R. C. Read (rcread(AT)math.uwaterloo.ca)

EXTENSIONS

a(0)=1 prepended and terms a(21) and beyond from Andrew Howroyd, Sep 05 2018

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 19 02:45 EDT 2019. Contains 323377 sequences. (Running on oeis4.)