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A185144 Number of not necessarily connected 4-regular simple graphs on n vertices with girth exactly 4. 9
0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 2, 12, 31, 220, 1606, 16829, 193900, 2452820, 32670331, 456028487, 6636066126, 100135577863, 1582718910743 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,11

LINKS

Table of n, a(n) for n=0..23.

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

FORMULA

a(n) = A184944(n) + A185044(n) = A185140(n,4).

CROSSREFS

Not necessarily connected k-regular simple graphs girth exactly 4: A198314 (any k), A185644 (triangle); fixed k: A026797 (k=2), A185134 (k=3), this sequence (k=4).

A185143 (g=3), A185144 (g=4).

Not necessarily connected 4-regular simple graphs with girth exactly g: A185140 (triangle); fixed g: A185143 (g=3), this sequence (g=4).

Sequence in context: A151366 A184944 A033886 * A185344 A237275 A087131

Adjacent sequences:  A185141 A185142 A185143 * A185145 A185146 A185147

KEYWORD

nonn,hard,more

AUTHOR

Jason Kimberley, Nov 04 2011

EXTENSIONS

Corrected by Jason Kimberley, Jan 03 2013

STATUS

approved

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Last modified July 18 07:46 EDT 2019. Contains 325136 sequences. (Running on oeis4.)