A198315 Number of, not necessarily connected, regular simple graphs on n vertices with girth exactly 5.

0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 2, 1, 3, 1, 9, 2, 50, 3, 453, 5, 5759, 14, 90693, 3926, 1736786, 4132004, 163458044, 4018022167, 119021971966

Offset

0,11

Links

Table of n, a(n) for n=0..28.

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

Formula

a(n) = A186745(n) + A210715(n).

a(n) = A185315(n) - A185316(n).

Crossrefs

Not necessarily connected regular simple graphs girth exactly g: A198313 (g=3), A198314 (g=4), this sequence (g=5), A198316 (g=6), A198317 (g=7), A198318 (g=8).

Sequence in context: A058036 A136179 A185176 * A126761 A090559 A088640

Adjacent sequences: A198312 A198313 A198314 * A198316 A198317 A198318

Keyword

nonn,more,hard

Author

Jason Kimberley, Dec 13 2012

Status

approved