A189569 -id:A189569 - cp's OEIS frontend

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A189570 Number of permutations p of 1,2,...,n satisfying |p(i+4)-p(i)|<>5 and |p(j+5)-p(j)|<>4 for all i=1..n-4, j=1..n-5.

Original entry on oeis.org

1, 1, 2, 6, 24, 120, 552, 2826, 17080, 117816, 943250, 8330356, 82954582, 915854808, 11147075946, 147948526182

Offset: 0

Vaclav Kotesovec, Apr 23 2011

a(n) is also the number of ways to place n nonattacking pieces rook + leaper[4,5] on an n X n chessboard.

V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech)

Cf. A137774, A189358, A189563, A189564, A189565, A189566, A189567, A189568, A189569.

Asymptotic: a(n)/n! ~ 1/e^4.

A189871 Number of ways to place n nonattacking composite pieces queen + leaper[3,5] on an n X n chessboard.

Original entry on oeis.org

1, 0, 0, 2, 10, 0, 8, 24, 72, 116, 384, 1660, 7344, 24364, 130408, 743360, 4242704, 27018788, 190618152, 1431986780, 11053915716

Offset: 1

Vaclav Kotesovec, Apr 29 2011

a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+3)-p(i)|<>5 AND |p(j+5)-p(j)|<>3 AND |p(m+k)-p(m)|<>k for all i>=1, j>=1, m>=1, k>=1, i+3<=n, j+5<=n, m+k<=n

V. Kotesovec, Number of ways of placing non-attacking queens, kings, bishops and knights (in English and Czech)
Wikipedia, Fairy chess piece

Cf. A051223, A189866, A189869, A189569, A189870

Showing 1-2 of 2 results.