1061948616domain: NAppears in sequencesT(n,k)=Number of (n+1)X(n+1) 0..k arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric.at n=23A187462Number of 4X4 0..n arrays with all the 2X2 subblocks nonsingular and the array of 2X2 subblock determinants symmetric.at n=4A187464