OFFSET
3,2
LINKS
Gunnar Brinkmann, Generating regular directed graphs, Discrete Math., 313 (2012), 1-7.
R. J. Mathar, OEIS A219889
Richard J. Mathar, 2-regular Digraphs of the Lovelock Lagrangian, arXiv:1903.12477 [math.GM], 2019.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
N. J. A. Sloane, Nov 30 2012
STATUS
approved