A185135 - OEIS

A185135

Number of not necessarily connected 3-regular simple graphs on 2n vertices with girth exactly 5.

0, 0, 0, 0, 0, 1, 2, 8, 48, 450, 5752, 90555, 1612917, 31297424, 652159986, 14499787794, 342646826428

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,7

LINKS

Table of n, a(n) for n=0..16.

Jason Kimberley, Index of sequences counting not necessarily connected k-regular simple graphs with girth exactly g

FORMULA

a(n) = A185335(n) - A185336(n).

a(n) = A006925(n) + A185035(n).

CROSSREFS

Not necessarily connected 3-regular simple graphs on 2n vertices with girth exactly g: A185130 (triangle); fixed g: A185133 (g=3), A185134 (g=4), this sequence (g=5), A185136 (g=6).

Sequence in context: A052667 A327904 A006925 * A238805 A005867 A280133

Adjacent sequences: A185132 A185133 A185134 * A185136 A185137 A185138

KEYWORD

nonn,hard,more

AUTHOR

Jason Kimberley, Mar 21 2012

STATUS

approved