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%I #6 Dec 18 2015 18:18:06
%S 1,2,50,5036,1650722,1726180511,5772723512117,61704243727319597,
%T 2108342605082097217766,230275999931688657463304318,
%U 80396959992514189225966415632361
%N Number of n X n 0..3 symmetric matrices with every element equal to zero or one horizontal and vertical neighbor, and new values 0..3 introduced in lower triangle row major order
%e Some solutions for n=4
%e ..0..1..0..1....0..1..2..0....0..1..2..0....0..1..1..3....0..1..0..3
%e ..1..2..0..2....1..0..2..1....1..0..3..0....1..2..0..3....1..2..0..2
%e ..0..0..3..0....2..2..1..0....2..3..2..3....1..0..3..2....0..0..3..0
%e ..1..2..0..3....0..1..0..1....0..0..3..2....3..3..2..1....3..2..0..3
%K nonn
%O 1,2
%A _R. H. Hardin_ Mar 29 2012
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