A185330 Irregular triangle E(n,g) counting not necessarily connected 3-regular simple graphs on 2n vertices with girth at least g.

1, 2, 1, 6, 2, 21, 6, 1, 94, 23, 2, 540, 112, 9, 1, 4207, 801, 49, 1, 42110, 7840, 455, 5, 516344, 97723, 5784, 32, 7373924, 1436873, 90940, 385, 118573592, 23791155, 1620491, 7574, 1, 2103205738, 432878091, 31478651, 181227, 3, 40634185402

Offset: 2

Author

Jason Kimberley, Oct 18 2012

Keywords

• nonn
• hard
• tabf

Comments

The first column is for girth at least 3. The row length is incremented to g-2 when 2n reaches A000066(g).

Examples

			1;
2, 1;
6, 2;
21, 6, 1;
94, 23, 2;
540, 112, 9, 1;
4207, 801, 49, 1;
42110, 7840, 455, 5;
516344, 97723, 5784, 32;
7373924, 1436873, 90940, 385;
118573592, 23791155, 1620491, 7574, 1;
2103205738, 432878091, 31478651, 181227, 3;
40634185402, 8544173926, 656784488, 4624502, 21;
847871397424, 181519645163, 14621878339, 122090545, 546, 1;
18987149095005, 4127569521160, 345975756388, 3328929960, 30368, 0;
		

Links

• Jason Kimberley, Table of i, a(i)=E(n,g) for i = 2..60 (n = 2..16)
• Jason Kimberley, Index of sequences counting not necessarily connected k-regular simple graphs with girth at least g

Crossrefs

Cf. A005638, A185334, A185304.