A189842 Number of ways to place n nonattacking composite pieces rook + rider[6,6] on an n X n chessboard.

1, 2, 6, 24, 120, 720, 4800, 34752, 280512, 2528256, 25282560, 278323200, 3242649600, 40330371072, 536528954880, 7633092132864

Offset

1,2

Comments

a(n) is also number of permutations p of 1,2,...,n satisfying |p(j+6k)-p(j)|<>6k for all j>=1, k>=1, j+6k<=n

Links

Table of n, a(n) for n=1..16.

Vaclav Kotesovec, Non-attacking chess pieces, 6ed, 2013, p. 661.

Wikipedia, Fairy chess piece

Crossrefs

Cf. A189271, A000170, A189838, A189839, A189840, A189841.

Sequence in context: A152359 A152362 A177543 * A189271 A152366 A147740

Adjacent sequences: A189839 A189840 A189841 * A189843 A189844 A189845

Keyword

nonn,hard

Author

Vaclav Kotesovec, Apr 29 2011

Status

approved