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

2,2

Comments

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

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

Example

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;

Crossrefs

Cf. A005638, A185334, A185304.

Sequence in context: A085592 A174421 A089849 * A217955 A325703 A321898

Adjacent sequences: A185327 A185328 A185329 * A185331 A185332 A185333

Keyword

nonn,hard,tabf

Author

Jason Kimberley, Oct 18 2012

Status

approved