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 A187424 #6 Jul 22 2025 10:44:06 %S A187424 76263,2142214,56472058,2183222530,72355701549 %N A187424 Number of (n+1)X7 0..2 arrays with every 2X2 subblock determinant equal to exactly one or two horizontal and vertical neighbor 2X2 subblock determinants. %C A187424 Column 6 of A187425 %e A187424 Some solutions for 3X7 %e A187424 ..0..0..2..1..0..0..0....0..0..2..1..0..0..2....0..0..1..1..1..0..2 %e A187424 ..0..0..2..2..2..1..2....0..0..1..1..1..2..2....0..0..0..1..2..0..0 %e A187424 ..0..1..2..1..0..0..0....0..2..2..0..1..2..0....0..0..1..1..1..0..2 %K A187424 nonn %O A187424 1,1 %A A187424 _R. H. Hardin_ Mar 09 2011