A198317 Number of, not necessarily connected, regular simple graphs on n vertices with girth exactly 7.

0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 3, 4, 4, 7, 5, 27, 7, 553, 10, 30379, 13, 1782854, 18, 95079100, 24, 4686063134, 32

Offset

0,22

Links

Table of n, a(n) for n=0..39.

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

Formula

a(n) = A186747(n) + A210717(n).

a(n) = A185317(n) - A185318(n).

Crossrefs

Not necessarily connected regular simple graphs girth exactly g: A198313 (g=3), A198314 (g=4), A198315 (g=5), A198316 (g=6), this sequence (g=7), A198318 (g=8).

Sequence in context: A225482 A004056 A284334 * A036822 A056099 A084848

Adjacent sequences: A198314 A198315 A198316 * A198318 A198319 A198320

Keyword

nonn,more,hard

Author

Jason Kimberley, Dec 18 2012

Status

approved