A185133 Number of not necessarily connected 3-regular simple graphs on 2n vertices with girth exactly 3.

0, 0, 1, 1, 4, 15, 71, 428, 3406, 34270, 418621, 5937051, 94782437, 1670327647, 32090011476, 666351752261, 14859579573845

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) = A005638(n) - A185334(n).

a(n) = A006923(n) + A185033(n).

Crossrefs

Not necessarily connected k-regular simple graphs girth exactly 3: A198313 (any k), A185643 (triangle); fixed k: A026796 (k=2), this sequence (k=3), A185143 (k=4), A185153 (k=5), A185163 (k=6).

Not necessarily connected 3-regular simple graphs on 2n vertices with girth exactly g: A185130 (triangle); fixed g: this sequence (g=3), A185134 (g=4), A185135 (g=5), A185136 (g=6).

Sequence in context: A366034 A027316 A085349 * A278640 A026992 A039764

Adjacent sequences: A185130 A185131 A185132 * A185134 A185135 A185136

Keyword

nonn,hard,more

Author

Jason Kimberley, Mar 21 2012

Status

approved