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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A187704 Number of (n+1)X(n+1) 0..5 arrays with each 2X2 subblock off diagonal and antidiagonal nonsingular and the array of 2X2 subblock determinants antisymmetric about the diagonal and antidiagonal.

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%I A187704 #6 Jul 22 2025 10:53:22
%S A187704 170,93476,2904,4225652,12898
%N A187704 Number of (n+1)X(n+1) 0..5 arrays with each 2X2 subblock off diagonal and antidiagonal nonsingular and the array of 2X2 subblock determinants antisymmetric about the diagonal and antidiagonal.
%C A187704 Column 5 of A187705
%e A187704 Some solutions for 4X4
%e A187704 ..3..2..0..0....0..0..1..0....2..2..4..0....1..1..0..0....2..2..4..0
%e A187704 ..3..2..2..4....3..2..1..0....5..5..5..0....1..1..2..4....2..2..2..0
%e A187704 ..5..2..2..2....2..2..1..2....0..2..2..2....3..1..2..3....0..2..2..2
%e A187704 ..0..0..2..2....4..4..1..2....0..5..0..0....0..0..2..3....0..4..2..2
%K A187704 nonn
%O A187704 1,1
%A A187704 _R. H. Hardin_ Mar 12 2011

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