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 A186556 #7 Jul 22 2025 10:24:54 %S A186556 60074,13360840,2976803436,663296784123,147795682647630, %T A186556 32931888185295104,7337893459883784628,1635031754050410331405, %U A186556 364318292831600934919531,81177517366244082982029095 %N A186556 Number of (n+1)X4 0..3 arrays with no 2X2 subblock commuting with any of its horizontal and vertical 2X2 subblock neighbors. %C A186556 Column 3 of A186558 %H A186556 R. H. Hardin, <a href="/A186556/b186556.txt">Table of n, a(n) for n = 1..200</a> %e A186556 Some solutions for 3X4 %e A186556 ..2..3..0..0....0..1..2..3....3..3..1..2....1..1..3..0....2..3..1..2 %e A186556 ..0..1..0..2....0..3..0..2....0..2..3..2....0..2..1..2....0..1..1..1 %e A186556 ..0..0..0..2....0..0..0..2....0..0..3..0....0..0..1..3....0..0..2..3 %K A186556 nonn %O A186556 1,1 %A A186556 _R. H. Hardin_ Feb 23 2011