A189869 Number of ways to place n nonattacking composite pieces queen + leaper[2,5] on an n X n chessboard.

1, 0, 0, 2, 10, 4, 28, 20, 56, 72, 288, 1304, 6368, 22884, 125864, 755412, 4565572, 29862256, 207238124, 1540506028, 11774180220

Offset

1,4

Comments

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

Links

Table of n, a(n) for n=1..21.

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

Wikipedia, Fairy chess piece

Crossrefs

Cf. A051223, A189866, A189867, A189868, A189567

Sequence in context: A319407 A199832 A189878 * A054790 A140393 A000170

Adjacent sequences: A189866 A189867 A189868 * A189870 A189871 A189872

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved