A219894 Number of directed 2-regular graphs on n nodes without directed 2-cycles.
1, 4, 9, 55, 453, 4357, 47598, 569769, 7371560, 102525991, 1525164223
Offset: 5
Links
- Gunnar Brinkmann, Generating regular directed graphs, Discrete Math., 313 (2012), 1-7.
Extensions
a(14) and a(15) from Brendan McKay, Mar 12 2019