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.
%I A187632 #6 Jul 22 2025 10:51:11 %S A187632 113,12104,106892,686589106,795758912 %N A187632 Number of (n+1)X(n+1) 0..4 arrays with the array of 2X2 subblock determinants antisymmetric under horizontal and vertical reflection and each non-centerline 2X2 subblock nonsingular. %C A187632 Column 4 of A187633 %e A187632 Some solutions for 4X4 %e A187632 ..3..1..3..0....0..4..4..4....0..4..3..2....0..2..4..0....1..4..4..4 %e A187632 ..3..0..0..1....1..0..0..1....3..0..0..4....2..0..0..1....1..0..0..1 %e A187632 ..1..0..0..3....2..0..0..1....4..0..0..3....1..0..0..2....4..0..0..1 %e A187632 ..3..3..1..0....1..2..4..0....2..3..4..2....2..4..2..0....4..1..4..3 %K A187632 nonn %O A187632 1,1 %A A187632 _R. H. Hardin_ Mar 12 2011