A184951 Irregular triangle C(n,g) counting the connected 5-regular simple graphs on 2n vertices with girth at least g.

1, 3, 60, 1, 7848, 1, 3459383, 7, 2585136675, 388, 2807105250897, 406824

Offset

3,2

Comments

The first column is for girth at least 3. The row length sequence starts: 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 4, 4. The row length is incremented to g-2 when 2n reaches A054760(5,g).

Links

Table of n, a(n) for n=3..14.

Jason Kimberley, Index of sequences counting connected k-regular simple graphs with girth at least g

Example

1;
3;
60, 1;
7848, 1;
3459383, 7;
2585136675, 388;
2807105250897, 406824;

Crossrefs

Connected 5-regular simple graphs with girth at least g: this sequence (triangle); chosen g: A006821 (g=3), A058275 (g=4), A205295 (g=5).

Connected 5-regular simple graphs with girth exactly g: A184950 (triangle); chosen g: A184953 (g=3), A184954 (g=4), A184955 (g=5).

Triangular arrays C(n,g) counting connected simple k-regular graphs on n vertices with girth at least g: A185131 (k=3), A184941 (k=4), this sequence (k=5), A184961 (k=6), A184971 (k=7), A184981 (k=8).

Sequence in context: A360837 A201184 A046024 * A081853 A183286 A195560

Adjacent sequences: A184948 A184949 A184950 * A184952 A184953 A184954

Keyword

nonn,hard,more,tabf

Author

Jason Kimberley, Jan 10 2012

Extensions

a(14) from Jason Kimberley, Dec 26 2012

Status

approved