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A185134 Number of, not necessarily connected, 3-regular simple graphs on 2n vertices with girth exactly 4. 12
0, 0, 0, 1, 2, 5, 21, 103, 752, 7385, 91939, 1345933, 22170664, 401399440, 7887389438, 166897766824, 3781593764772 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

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) = A185334(n) - A185335(n).

a(n) = A006924(n) + A185034(n).

CROSSREFS

Not necessarily connected k-regular simple graphs girth exactly 4: A198314 (any k), A185644 (triangle); fixed k: A026797 (k=2), this sequence (k=3), A185144 (k=4).

Not necessarily connected 3-regular simple graphs on 2n vertices with girth exactly g: A185130 (triangle); fixed g: A185133 (g=3), this sequence (g=4), A185135 (g=5), A185136 (g=6).

Sequence in context: A115087 A008981 A008982 * A130471 A002628 A020129

Adjacent sequences:  A185131 A185132 A185133 * A185135 A185136 A185137

KEYWORD

nonn,hard,more

AUTHOR

Jason Kimberley, Mar 21 2012

STATUS

approved

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Last modified March 19 13:08 EDT 2019. Contains 321330 sequences. (Running on oeis4.)