A128042 Triangle read by columns: number of n-node (unlabeled) connected graphs with girth k, for n >= 3, k >= 3.

1, 3, 1, 15, 2, 1, 93, 11, 1, 1, 794, 41, 5, 1, 1, 10850, 220, 16, 6, 1, 1, 259700, 1243, 66, 17, 5, 1, 1, 11706739, 9368, 266, 69, 15, 6, 1, 1, 1006609723, 89049, 1235, 239, 58, 18, 6, 1, 1, 164058686415, 1135894, 6350, 962, 202, 74, 19, 7, 1, 1

Offset: 3

Author

Keith Briggs, May 05 2007

Keywords

• nonn
• tabl

Examples

			Number of n-node (unlabeled) connected graphs with girth k:
.k..|.n=........3........4........5........6........7........8........9........10
---------------------------------------------------------------------------------
.0..|...........0........0........0........0........0........0........0.........0
.1..|...........0........0........0........0........0........0........0.........0
.2..|...........0........0........0........0........0........0........0.........0
.3..|...........1........3.......15.......93......794....10850...259700..11706739
.4..|...........0........1........2.......11.......41......220.....1243......9368
.5..|...........0........0........1........1........5.......16.......66.......266
.6..|...........0........0........0........1........1........6.......17........69
.7..|...........0........0........0........0........1........1........5........15
.8..|...........0........0........0........0........0........1........1.........6
.9..|...........0........0........0........0........0........0........1.........1
10..|...........0........0........0........0........0........0........0.........1
11..|...........0........0........0........0........0........0........0.........0
		

Links

• Georg Grasegger, Table of n, a(n) for n = 3..122

Crossrefs

Sequences for k=3..6 are A128240, A128241, A128242, A128243.

Cf. A128041, A006787, A128236, A128237, A128238, A128239.

Cf. A325455 (circumference).

Programs

nauty

geng -c $n | countg --ng
# Martin Fuller, May 03 2015

Extensions

Corrected and extended by Martin Fuller, May 01 2015