A210819 - OEIS

A210819

Number of (n+1) X (n+1) 0..3 symmetric matrices containing all values 0..3 with every 2 X 2 subblock having one, two or three distinct values, and new values 0..3 introduced in lower triangle row major order.

%I #7 Mar 15 2023 14:41:37

%S 0,49,23161,22911278,69542484194,729154389280269,27471650645869518237,

%T 3762964490348482852461426,1879310211105558770807436764190,

%U 3424003001550934968214802269585406825

%N Number of (n+1) X (n+1) 0..3 symmetric matrices containing all values 0..3 with every 2 X 2 subblock having one, two or three distinct values, and new values 0..3 introduced in lower triangle row major order.

%H R. H. Hardin, <a href="/A210819/b210819.txt">Table of n, a(n) for n = 1..11</a>

%e Some solutions for n=3

%e ..0..1..1..1....0..0..1..1....0..1..2..3....0..1..0..3....0..1..1..2

%e ..1..1..1..3....0..1..1..1....1..2..1..3....1..2..2..2....1..2..0..2

%e ..1..1..2..3....1..1..1..2....2..1..0..1....0..2..2..0....1..0..3..0

%e ..1..3..3..2....1..1..2..3....3..3..1..2....3..2..0..2....2..2..0..1

%K nonn

%O 1,2

%A _R. H. Hardin_, Mar 27 2012