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

Offset: 0

Author

Jason Kimberley, Mar 21 2012

Keywords

• nonn
• hard
• more

Links

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

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).

Formula

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

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