OFFSET
2,2
COMMENTS
These graphs may have loops, whereas A219889 does not admit them. Both sequences do not admit multiedges. - R. J. Mathar, Mar 27 2019
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Richard J. Mathar, 2-regular Digraphs of the Lovelock Lagrangian, arXiv:1903.12477 [math.GM], 2019.
M. V. S. Ramanath and T. R. Walsh, Enumeration and generation of a class of regular digraphs, J. Graph Theory 11 (1987), no. 4, 471-479. (Annotated scanned copy)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved