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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A068932 a(n) = number of disconnected regular graphs with n nodes. 11
0, 1, 1, 2, 1, 3, 2, 5, 4, 9, 7, 23, 18, 74, 106, 619, 2076, 22526, 112834, 4799825, 31138965, 4207943011, 115979718015, 13482672647959 (list; graph; refs; listen; history; internal format)
OFFSET

1,4

COMMENTS

A graph is called regular if every node has the same number of edges.

Row sums of A068933.

FORMULA

a(n) = A005176(n) - A005177(n).

CROSSREFS

Cf. A005176, A005177, A068933.

Sequence in context: A034392 A181531 A034393 * A151533 A128100 A035579

Adjacent sequences:  A068929 A068930 A068931 * A068933 A068934 A068935

KEYWORD

hard,more,nonn

AUTHOR

David Wasserman (dwasserm(AT)earthlink.net), Mar 08 2002

EXTENSIONS

a(22) corrected and a(23) added by J. S. Kimberley (Jason.Kimberley(AT)newcastle.edu.au), Sep 28 2009

a(24) also from Jason Kimberley (Jason.Kimberley(AT)newcastle.edu.au), Nov 24 2009

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Puzzles | Hot | Classics
Recent Additions | More pages | Superseeker | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified February 15 10:56 EST 2012. Contains 205763 sequences.