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%I #7 Jan 14 2017 09:40:27
%S 2,24,1986,782948,1291076970,8783684627835,245608218357699105,
%T 28056029360014523631654,13030390694954764597618159782
%N 1/4 the number of (n+1) X (n+1) binary arrays with equal numbers of 2 X 2 subblocks with sums 1 and 3.
%C Diagonal of A184604.
%e Some solutions for 3 X 3:
%e ..1..0..0....0..0..1....0..1..1....1..1..1....1..0..0....1..0..0....1..1..1
%e ..1..1..0....1..1..0....1..0..0....1..0..0....1..0..1....1..0..1....0..0..0
%e ..1..0..0....1..1..0....0..1..1....0..1..0....1..1..0....0..1..1....1..1..1
%K nonn
%O 1,1
%A _R. H. Hardin_, Jan 18 2011
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