OFFSET
1,3
COMMENTS
a(n) is also the number of cube root two-graphs, up to isomorphism.
LINKS
Y. Cheng and A. L. Wells, Switching classes of directed graphs, Journal of Combinatorial Theory, Series B, Vol. 40-2 (1986), p. 169-186.
Akihiro Higashitani and Kenta Ueyama, Combinatorics of graded module categories over skew polynomial algebras at roots of unity, arXiv:2409.10904 [math.RA], 2024. See p. 11.
T. R. Hoffman and J. P. Solazzo, Complex two-graphs via equiangular tight frames, arXiv preprint, arXiv:1408.0334 [math.CO], 2014-2017.
CROSSREFS
KEYWORD
nonn,more,changed
AUTHOR
Thomas R. Hoffman, Aug 05 2014
EXTENSIONS
a(8)-a(12) added by Andrew Howroyd, Aug 31 2018
a(1)=a(2)=1 from Higashitani and Ueyama prepended by Stefano Spezia, Sep 21 2024
STATUS
approved