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A198314 Number of, not necessarily connected, regular simple graphs on n vertices with girth exactly 4. 9
0, 0, 0, 0, 1, 0, 1, 0, 4, 1, 8, 3, 37, 33, 335, 1610, 17985, 193911, 2867313, 32674066, 1581626531, 6705889862 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,9

LINKS

Table of n, a(n) for n=0..21.

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

FORMULA

a(n) = A186744(n) + A210714(n).

a(n) = A185314(n) - A185315(n).

CROSSREFS

Not necessarily connected k-regular simple graphs girth exactly 4: this sequence (any k), A185644 (triangle); fixed k: A026797 (k=2), A185134 (k=3), A185144 (k=4).

Not necessarily connected regular simple graphs girth exactly g: A198313 (g=3), this sequence (g=4), A198315 (g=5), A198316 (g=6), A198317 (g=7), A198318 (g=8).

Sequence in context: A145917 A201661 A263498 * A105534 A021243 A096051

Adjacent sequences:  A198311 A198312 A198313 * A198315 A198316 A198317

KEYWORD

nonn,more,hard

AUTHOR

Jason Kimberley, Dec 12 2012

EXTENSIONS

a(10) corrected from 9 to 8 by Jason Kimberley, Feb 22 2013

STATUS

approved

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Last modified January 17 12:50 EST 2020. Contains 330958 sequences. (Running on oeis4.)