A255599 Number of (semi-)regular tournaments of order n.

1, 1, 1, 1, 1, 5, 3, 85, 15, 13333, 1223, 19434757, 1495297, 276013571133, 18400989629

Offset

1,6

Comments

A tournament of odd order n is regular if the out-degree of each vertex is (n-1)/2. A tournament of even order n is semi-regular if the out-degree of each vertex is n/2-1 or n/2.

Links

Table of n, a(n) for n=1..15.

B. McKay, Digraphs

Crossrefs

Cf. A000568, A096368.

Sequence in context: A258091 A370551 A350213 * A180403 A343582 A267512

Adjacent sequences: A255596 A255597 A255598 * A255600 A255601 A255602

Keyword

nonn,hard,more

Author

Danny Rorabaugh, Feb 27 2015

Extensions

a(1)-a(2) prepended and a(14)-a(15) added by Brendan McKay, Mar 21 2019

Status

approved