Published online by Cambridge University Press: 26 February 2010
The number of self-complementary graphs and the number
of self-complementary digraphs were expressed by Read [4] in terms of cycle indexes of the appropriate pair groups. These formulas for
and
, together with a modification of the method employed by Oberschelp [3] for graphs, can be used to obtain estimates for
and
and a bound on the error. For graph theoretic definitions not given here, we refer to the book [2].