OFFSET
1,4
COMMENTS
In fairy chess the leaper [2,3] is called a zebra.
a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+2)-p(i)|<>3 AND |p(j+3)-p(j)|<>2 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+2<=n, j+3<=n, m+k<=n
LINKS
V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech)
Wikipedia, Fairy chess piece
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Vaclav Kotesovec, Apr 29 2011
STATUS
approved