A189857 - OEIS

A189857

Number of ways to place n nonattacking composite pieces rook + rider[2,6] on an n X n chessboard.

%I #6 Sep 12 2015 11:00:25

%S 1,2,6,24,120,720,2952,16064,104800,816160,7327728,74031176,621684168,

%T 5950876288,64694543120,777746708096

%N Number of ways to place n nonattacking composite pieces rook + rider[2,6] on an n X n chessboard.

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

%H V. Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Number of ways of placing non-attacking queens, kings, bishops and knights</a> (in English and Czech)

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a>

%Y Cf. A000170, A189854, A189855, A189856, A189853

%K nonn,hard

%O 1,2

%A _Vaclav Kotesovec_, Apr 29 2011