Number of (n+1)X(n+1) 0..3 symmetric matrices containing all values 0..3 with every 2X2 subblock having one, two or four distinct values, and new values 0..3 introduced in lower triangle row major order.

A210821

Number of (n+1)X(n+1) 0..3 symmetric matrices containing all values 0..3 with every 2X2 subblock having one, two or four distinct values, and new values 0..3 introduced in lower triangle row major order.