OFFSET
3,1
COMMENTS
A permutation is 3-equitable if no omega in S_3 appears more than ceiling(binomial(n,3)/6) times or fewer than floor(binomial(n,3)/6) times.
E.g., 2143 contains 214, 213--213 permutations--and 243 and 143--both 132 permutations.
This is a generalization of the Kendall-Mann numbers A000140.
LINKS
Sunil Abraham, Maple program
EXAMPLE
The only 3-equitable permutations in S_4: [3, 1, 4, 2], [2, 4, 1, 3].
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Sunil Abraham (sunil.abraham(AT)lmh.ox.ac.uk), Aug 08 2008
STATUS
approved