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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

(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) = 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: A027316 A085349 A385040 * A278640 A026992 A039764

Adjacent sequences: A185130 A185131 A185132 * A185134 A185135 A185136

KEYWORD

nonn,hard,more

AUTHOR

Jason Kimberley, Mar 21 2012

STATUS

approved

URL: https://oeis.org/A185133

⇱ A185133 - OEIS