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A210902 Number of n X n 0..2 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order 0

%I

%S 1,3,17,252,6328,297609,25886499,4205102578,1265408306700,

%T 707818003940086,733897633220152333,1410044723992401143016

%N Number of n X n 0..2 symmetric matrices with every element equal to zero, two or three horizontal and vertical neighbors, and new values 0..2 introduced in lower triangle row major order

%e Some solutions for n=4

%e ..0..1..2..0....0..0..0..0....0..1..0..0....0..1..2..2....0..1..2..1

%e ..1..2..0..1....0..1..0..0....1..2..0..0....1..0..2..2....1..0..1..0

%e ..2..0..2..0....0..0..1..0....0..0..1..0....2..2..0..1....2..1..2..1

%e ..0..1..0..1....0..0..0..0....0..0..0..0....2..2..1..2....1..0..1..0

%K nonn

%O 1,2

%A _R. H. Hardin_ Mar 29 2012

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Last modified May 26 04:26 EDT 2022. Contains 354074 sequences. (Running on oeis4.)