231230

Appears in sequences

• Number of (n+1) X (1+1) 0..1 arrays with every element equal to some horizontal, vertical or antidiagonal neighbor, with top left element zero.at n=9A232031
• Number of nonequivalent binary matrices with 4 columns and any number of nonzero rows with n ones in every column up to permutation of rows and columns.at n=11A331720