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A189841
Number of ways to place n nonattacking composite pieces rook + rider[5,5] on an n X n chessboard.
2
1, 2, 6, 24, 120, 672, 4128, 28992, 231936, 2088960, 20017152, 207208704, 2326900992, 28338241536, 373152276480, 5206300028928
OFFSET
1,2
COMMENTS
a(n) is also number of permutations p of 1,2,...,n satisfying |p(j+5k)-p(j)|<>5k for all j>=1, k>=1, j+5k<=n
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Vaclav Kotesovec, Apr 29 2011
STATUS
approved