A187703 - OEIS

%I #6 Jan 20 2024 16:41:25

%S 113,31461,1718,875696,4612

%N Number of (n+1) X (n+1) 0..4 arrays with each 2 X 2 subblock off diagonal and antidiagonal nonsingular and the array of 2 X 2 subblock determinants antisymmetric about the diagonal and antidiagonal.

%C Column 4 of A187705.

%e Some solutions for 4 X 4

%e ..0..2..1..1....0..0..1..0....2..2..4..2....0..3..0..0....4..3..4..4

%e ..0..1..1..1....3..2..1..0....2..2..2..1....0..1..1..2....4..3..3..3

%e ..1..1..1..0....2..2..1..2....2..4..4..4....3..3..3..3....3..3..3..4

%e ..3..3..4..0....4..4..1..2....2..4..3..3....0..0..1..1....1..1..0..0

%Y Cf. A187705.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 12 2011