A187708 - OEIS

A187708

Number of 5 X 5 0..n 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.

%I #10 Jun 23 2026 12:55:56

%S 34,5030,81456,875696,4225652,22532156,67940472,225606354,577091334,

%T 1469652502

%N Number of 5 X 5 0..n 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 Row 4 of A187705.

%e Some n=3 solutions for 5 X 5

%e ..0..1..1..1..2....2..2..1..2..2....2..2..1..2..2....0..0..1..0..0

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

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

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

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

%Y Cf. A187705.

%K nonn

%O 1,1

%A _R. H. Hardin_, Mar 12 2011