A189863 - OEIS

A189863

Number of ways to place n nonattacking composite pieces rook + rider[5,6] on an n X n chessboard.

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

%S 1,2,6,24,120,720,4176,26140,185084,1491098,13285034,132514356,

%T 1321161252,14181339764,164574628260,2057033314380

%N Number of ways to place n nonattacking composite pieces rook + rider[5,6] on an n X n chessboard.

%C a(n) is also number of permutations p of 1,2,...,n satisfying |p(i+5k)-p(i)|<>6k AND |p(j+6k)-p(j)|<>5k for all i>=1, j>=1, k>=1, i+5k<=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, A189853, A189857, A189860, A189862

%K nonn,hard

%O 1,2

%A _Vaclav Kotesovec_, Apr 29 2011