Number of n X n symmetric 0..2 arrays with no element equal to any horizontal or vertical neighbor, containing at least one 2 and with new values 0..2 introduced in lower triangular row major order.

A193308

Number of n X n symmetric 0..2 arrays with no element equal to any horizontal or vertical neighbor, containing at least one 2 and with new values 0..2 introduced in lower triangular row major order.