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A189881
Number of ways to place n nonattacking composite pieces queen + rider[4,5] on an n X n chessboard.
0
1, 0, 0, 2, 10, 4, 12, 32, 96, 144, 528, 1712, 7472, 24500, 103536, 486020, 2218808, 11113020, 59242576, 342584556, 1981826412
OFFSET
1,4
COMMENTS
a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+4k)-p(i)|<>5k AND |p(j+5k)-p(j)|<>4k AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+4k<=n, j+5k<=n, m+k<=n
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Vaclav Kotesovec, Apr 29 2011
STATUS
approved