0,4

R. L. Davis, Structure of dominance relations, Bull. Math. Biophys., 16 (1954), 131-140.

M. Goldberg and J. W. Moon, On the composition of two tournaments. Duke Math. J. 37 1970 323-332.

F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, pp. 126 and 245.

J. W. Moon, Topics on Tournaments. Holt, NY, 1968, p. 87.

K. B. Reid and L. W. Beineke "Tournaments", pp. 169-204 in L. W. Beineke and R. J. Wilson, editors, Selected Topics in Graph Theory, Academic Press, NY, 1978.

J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 157 and 523.

Keith Briggs, Table of n, a(n) for n = 0..76

P. J. Cameron, Sequences realized by oligomorphic permutation groups, J. Integ. Seqs. Vol. 3 (2000), #00.1.5.

Brendan McKay, Combinatorial Data.

Eric Weisstein's World of Mathematics, Tournament

Index entries for sequences related to tournaments

with(combinat):with(numtheory): for n from 1 to 30 do p:=partition(n): s:=0:for k from 1 to nops(p) do ex:=1:for i from 1 to nops(p[k]) do if p[k][i] mod 2=0 then ex:=0:break:fi:od:

if ex=1 then q:=convert(p[k], multiset): for i from 1 to n do a(i):=0:od:for i from 1 to nops(q) do a(q[i][1]):=q[i][2]:od:

c:=1:ord:=1:for i from 1 to n do c:=c*a(i)!*i^a(i): if a(i)<>0 then ord:=lcm(ord, i):fi:od: g:=0:for d from 1 to ord do if ord mod d=0 then g1:=0:for del from 1 to n do if d mod del=0 then g1:=g1+del*a(del):fi:od:g:=g+phi(ord/d)*g1*(g1-1):fi:od: s:=s+2^(g/ord/2)/c:fi:

od: print(n, s); od: (Vladeta Jovovic)

Cf. A006125 for the labeled analogue, A051337.

Adjacent sequences: A000565 A000566 A000567 this_sequence A000569 A000570 A000571

Sequence in context: A158569 A020106 A099928 this_sequence A128648 A128646 A155747

nonn,nice,easy

N. J. A. Sloane (njas(AT)research.att.com).

More terms from Vladeta Jovovic (vladeta(AT)Eunet.yu)

Harary and Palmer give incorrect values for a(24) and a(25); the correct values are a(24) = 195692027657521876084316842660833482785173437775365039898624 and a(25) = 131326696677895002131450257709457767457170027052967027982788816896. - Vladeta Jovovic (vladeta(AT)Eunet.yu), Apr 08 2001