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A189878 Number of ways to place n nonattacking composite pieces queen + rider[2,5] on an n X n chessboard. 2
1, 0, 0, 2, 10, 4, 28, 20, 56, 72, 200, 644, 2940, 9152, 39200, 166100, 739924, 3586840, 18640500, 107580592, 547737844, 3080550788 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+2k)-p(i)|<>5k AND |p(j+5k)-p(j)|<>2k AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+2k<=n, j+5k<=n, m+k<=n
LINKS
CROSSREFS
Sequence in context: A189872 A319407 A199832 * A189869 A054790 A140393
KEYWORD
nonn,hard
AUTHOR
Vaclav Kotesovec, Apr 29 2011
STATUS
approved

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Last modified March 28 09:04 EDT 2024. Contains 371240 sequences. (Running on oeis4.)