cp's OEIS Frontend

A220350 Number of ways of putting 2n^2 counters on distinct squares of a 2n x 2n board so that no row, column or main diagonal contains more than n counters.

%I A220350 #6 Dec 14 2012 12:10:55
%S A220350 0,33,112160,43346734009,2441203940002594824
%N A220350 Number of ways of putting 2n^2 counters on distinct squares of a 2n x 2n board so that no row, column or main diagonal contains more than n counters.
%H A220350 <a href="http://www.bmoc.maths.org/home/bmo1-2013.pdf">2012/13 British Mathematical Olympiad Round 1</a>, problem 1.
%e A220350 Configurations for n=2 (4x4 board) (o = counter):
%e A220350 .
%e A220350 oo.. (2 orientations)
%e A220350 o.o.
%e A220350 .o.o
%e A220350 ..oo
%e A220350 .
%e A220350 .o.o (2 orientations)
%e A220350 oo..
%e A220350 ..oo
%e A220350 o.o.
%e A220350 .
%e A220350 oo.. (4 orientations)
%e A220350 o..o
%e A220350 ..oo
%e A220350 .oo.
%e A220350 .
%e A220350 oo.. (4 orientations)
%e A220350 ..oo
%e A220350 oo..
%e A220350 ..oo
%e A220350 .
%e A220350 oo.. (4 orientations)
%e A220350 ..oo
%e A220350 ..oo
%e A220350 oo..
%e A220350 .
%e A220350 oo.. (8 orientations)
%e A220350 ..oo
%e A220350 o..o
%e A220350 .oo.
%e A220350 .
%e A220350 o.o. (4 orientations)
%e A220350 .o.o
%e A220350 .o.o
%e A220350 o.o.
%e A220350 .
%e A220350 o.o. (4 orientations)
%e A220350 .o.o
%e A220350 o..o
%e A220350 .oo.
%e A220350 .
%e A220350 .oo. (1 orientation)
%e A220350 o..o
%e A220350 o..o
%e A220350 .oo.
%K A220350 hard,nonn
%O A220350 1,2
%A A220350 _Joseph Myers_, Dec 11 2012