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 A186212 #7 Jul 22 2025 10:19:29 %S A186212 175,1969,18873,197619,2008031,20738153,213108423,2194753479, %T A186212 22587046821,232531438315,2393657704397,24641409679961, %U A186212 253666806143927,2611352484956083,26882320490736795,276737910767834565 %N A186212 Number of (n+1)X3 0..2 arrays with every 2X2 subblock determinant equal to some horizontal or vertical neighbor 2X2 subblock determinant. %C A186212 Column 2 of A186218 %H A186212 R. H. Hardin, <a href="/A186212/b186212.txt">Table of n, a(n) for n = 1..200</a> %e A186212 Some solutions for 5X3 %e A186212 ..0..0..1....0..0..0....1..0..2....0..0..0....2..0..1....1..0..2....0..0..2 %e A186212 ..0..0..2....2..0..2....0..0..0....1..0..0....0..0..0....0..0..1....1..0..1 %e A186212 ..1..0..1....2..0..0....1..0..2....1..0..0....2..0..1....1..0..2....0..0..1 %e A186212 ..0..0..1....2..0..2....2..0..0....2..0..2....1..0..2....0..0..0....0..0..2 %e A186212 ..0..0..2....0..0..1....0..0..1....0..0..2....2..0..2....1..1..0....1..0..1 %K A186212 nonn %O A186212 1,1 %A A186212 _R. H. Hardin_ Feb 15 2011