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%I #6 Dec 18 2015 18:17:32
%S 1,4,85,484,3661,28900,137845,1322500
%N One quarter the number of n X n toroidal 0..3 arrays with each element having the sum of its vertical neighbors equal to the sum of its horizontal neighbors
%C One quarter the number of solutions in 0..3 of a 1-d velocity-one wave equation utt=uxx on a periodic grid
%C Diagonal of A184101
%e Some solutions for 5X5
%e ..2..0..3..3..0....1..2..1..1..3....2..1..1..2..1....3..1..2..1..3
%e ..0..2..0..3..3....2..1..2..3..0....1..0..2..2..2....2..3..2..2..1
%e ..3..0..2..0..3....0..2..3..1..2....0..2..1..2..2....1..3..3..2..1
%e ..3..3..0..2..0....2..2..1..2..1....3..1..2..1..0....2..1..3..2..2
%e ..0..3..3..0..2....3..1..1..1..2....1..3..1..0..2....2..2..0..3..3
%K nonn
%O 1,2
%A _R. H. Hardin_ Jan 09 2011
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