3080194domain: NAppears in sequencesa(n) = 1*T(n,0) + 2*T(n,1) + ... + (2n+1)*T(n,2n), T given by A027926.at n=16A027992Number of (n+1)X(n+1) 0..2 arrays with every 2X2 subblock having nonzero determinant and commuting with every horizontal or vertical neighbor.at n=17A207141