%I #9 Dec 05 2016 05:10:40
%S 0,0,0,27,4860,164423,2651890,25981150,180378380,971905679,4316504623,
%T 16457726539,55463445891,168782705327,471407278652,1223710587908,
%U 2982045310010
%N Number of non-equivalent ways to place 7 non-attacking ferses on an n X n board.
%C A fers is a leaper [1, 1].
%C Rotations and reflections of placements are not counted. If they are to be counted, see A201248.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Fairy_chess_piece">Fairy chess piece</a>
%e There are 27 non-equivalent ways to place 7 non-attacking ferses (X) on a 4 X 4 board, rotations and reflections being ignored, e.g., these two:
%e XXXX X.XX
%e .... ....
%e XXX. X.X.
%e .... X.X.
%Y Cf. A201248, A232567 (2 ferses), A278682 (3 ferses), A278683 (4 ferses), A278684 (5 ferses), A278685 (6 ferses), A278687, A278688.
%K nonn,more
%O 1,4
%A _Heinrich Ludwig_, Dec 02 2016