OFFSET
1,4
COMMENTS
A fers is a leaper [1, 1].
Rotations and reflections of placements are not counted. If they are to be counted, see A201248.
LINKS
Wikipedia, Fairy chess piece
EXAMPLE
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:
XXXX X.XX
.... ....
XXX. X.X.
.... X.X.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Heinrich Ludwig, Dec 02 2016
STATUS
approved