A184970 Irregular triangle C(n,g) counting the connected 7-regular simple graphs on 2n vertices with girth exactly g.

1, 5, 1547, 21609300, 1, 733351105933, 1

Offset: 4

Author

Jason Kimberley, Feb 25 2011

Keywords

• nonn
• hard
• more
• tabf

Comments

The first column is for girth exactly 3. The row length sequence starts: 1, 1, 1, 2, 2, 2, 2, 2. The row length is incremented to g-2 when 2n reaches A054760(7,g).

Examples

			1;
5;
1547;
21609300, 1;
733351105933, 1;
?, 8;
?, 741;
?, 2887493;
		

Links

• Jason Kimberley, Index of sequences counting connected k-regular simple graphs with girth exactly g
• Jason Kimberley, Incomplete table of i, n, g, C(n,g)=a(i) for row n = 4..11

Crossrefs

Connected 7-regular simple graphs with girth at least g: A184971 (triangle); chosen g: A014377 (g=3), A181153 (g=4).

Connected 7-regular simple graphs with girth exactly g: this sequence (triangle); chosen g: A184973 (g=3), A184974 (g=4).

Triangular arrays C(n,g) counting connected simple k-regular graphs on n vertices with girth exactly g: A198303 (k=3), A184940 (k=4), A184950 (k=5), A184960 (k=6), this sequence (k=7), A184980 (k=8).