The OEIS is supported by the many generous donors to the OEIS Foundation.


(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A123553 A "king chicken" in a tournament graph (a directed labeled graph on n nodes with a single arc between every pair of nodes) is a player A who for any other player B either beats B directly or beats someone who beats B. Sequence gives total number of king chickens in all 2^(n(n-1)/2) tournaments. 4
1, 2, 12, 128, 2680, 109824, 8791552 (list; graph; refs; listen; history; text; internal format)



H. G. Landau showed in 1951 that there may be several king chickens in a tournament and that a player is a king chicken if he has the highest score. The converse is not true and there can be more king chickens than highest scorers. The smallest example has 4 players: A beats B and C, B beats C and D, C beats D, D beats A; D is a king chicken despite having fewer points than A and B. Maurer showed in 1980 that there is one king chicken if one player beats all others and otherwise there are at least three.


Table of n, a(n) for n=1..7.

S. B. Maurer, The king chicken theorems, Math. Mag., 53 (1980), 67-80.

Index entries for sequences related to tournaments


a(n) >= A006125(n)*3 - A006125(n-1)*n*2 with equality for n<=4.


For n = 3 there are 8 tournaments: six of the form A beats B and C and B beats C, with one king chicken (A) and two of the form A beats B beats C beats A, with three king chickens each (A or B or C), for a total of 6*1 + 2*3 = 12.


Cf. A006125, A013976, A123553, A125032, A125031 (highest scorers)w, A123903 (Emperors).

Sequence in context: A259267 A014235 A098628 * A354493 A079199 A303926

Adjacent sequences: A123550 A123551 A123552 * A123554 A123555 A123556




N. J. A. Sloane, Nov 14 2006


Corrected and edited by Martin Fuller, Nov 16 2006



Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 31 18:36 EDT 2023. Contains 361672 sequences. (Running on oeis4.)