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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.

A187707 Number of 4X4 0..n 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 A187707 #6 Jul 22 2025 10:53:43
%S A187707 2,72,322,1718,2904,9834,13324,31000,49910,84760,98226,211526,234336,
%T A187707 325654,454612,691052,742006,1152832,1224538,1765938
%N A187707 Number of 4X4 0..n arrays with each 2X2 subblock off diagonal and antidiagonal nonsingular and the array of 2X2 subblock determinants antisymmetric about the diagonal and antidiagonal.
%C A187707 Row 3 of A187705
%e A187707 Some n=3 solutions for 4X4
%e A187707 ..1..1..0..0....1..3..0..0....0..0..1..1....0..3..1..2....0..2..0..0
%e A187707 ..2..2..2..2....1..3..2..3....1..1..1..1....0..1..1..2....0..2..1..3
%e A187707 ..2..1..1..0....3..3..2..0....0..1..1..2....2..2..2..2....1..2..1..1
%e A187707 ..0..0..2..0....0..0..2..0....0..1..0..0....0..0..1..1....1..2..2..2
%K A187707 nonn
%O A187707 1,1
%A A187707 _R. H. Hardin_ Mar 12 2011

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