A224886 - OEIS

%I #18 Sep 13 2013 21:30:06

%S 0,1,2,4,13

%N Number of unlabeled tournaments which do not contain a transitive n-tournament.

%C The empty tournament is considered.

%H John W. Moon, <a href="http://www.gutenberg.org/ebooks/42833">Topics on tournaments</a>, Holt, Rinehard and Winston (1968).

%e For n=4, the a(4)= 13 solutions are the 5 tournaments on at most three vertices (the empty tournament is counted), 3 tournaments on four vertices, 3 tournaments on five vertices, 1 tournament on seven vertices (the Paley tournament on P_7 on seven vertices) and 1 tournament on six vertices (the tournament obtained from P_7 by deleting one vertex).

%e Notice that the tournaments on at most six vertices are listed in the Moon reference.

%K nonn,more

%O 0,3

%A _Houmem Belkhechine_, Jul 24 2013