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A244284
Number of ways to place n nonattacking zebras on an n X n chessboard.
4
1, 6, 84, 1168, 20502, 525796, 18939708, 802444170, 38934305898, 2170312156170
OFFSET
1,2
COMMENTS
Zebra is a (fairy chess) leaper [2,3].
LINKS
FORMULA
a(n) ~ n^(2*n)/n! * exp(-9/2).
KEYWORD
nonn,hard,more
AUTHOR
Vaclav Kotesovec, Jun 25 2014
STATUS
approved