Number of 3X3 0..n arrays with each 2X2 subblock nonsingular and the array of 2X2 subblock determinants symmetric about the diagonal and antidiagonal.
A187671
Number of 3X3 0..n arrays with each 2X2 subblock nonsingular and the array of 2X2 subblock determinants symmetric about the diagonal and antidiagonal.
Terms
- a(0) =24a(1) =550a(2) =4044a(3) =17716a(4) =56080a(5) =150166a(6) =336776a(7) =702408a(8) =1330728a(9) =2385910a(10) =3973400a(11) =6550700a(12) =10068336a(13) =15247986a(14) =22545648a(15) =32579360a(16) =45246528a(17) =62983046a(18) =84524916a(19) =113900920a(20) =150370548a(21) =195521534a(22) =249456396a(23) =321513812a(24) =404142192a(25) =504603526
External references
- oeis: A187671