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 A205757 #7 Jul 22 2025 19:01:05 %S A205757 12574,82992,507035,3869807,28155907,233316016,1885888870,16599011784, %T A205757 144835219234,1335751969435,12319659225966,117640826011747, %U A205757 1127388561521481,11036054002196311,108508423769699944 %N A205757 Number of 6X(n+1) 0..2 arrays with every 2X2 subblock having the same number of equal edges as its horizontal neighbors and a different number from its vertical neighbors, and new values 0..2 introduced in row major order. %C A205757 Row 5 of A205753 %H A205757 R. H. Hardin, <a href="/A205757/b205757.txt">Table of n, a(n) for n = 1..121</a> %e A205757 Some solutions for n=4 %e A205757 ..0..1..0..2..2....0..0..0..0..0....0..1..1..0..1....0..1..0..0..1 %e A205757 ..0..0..0..2..0....0..1..0..2..0....0..1..0..0..0....0..0..0..1..1 %e A205757 ..1..2..1..2..1....2..2..0..1..1....0..2..2..1..2....2..1..2..2..0 %e A205757 ..2..2..2..2..2....0..0..0..0..1....2..2..1..1..1....2..1..2..0..0 %e A205757 ..2..2..2..2..2....1..2..1..2..2....1..0..0..2..0....2..0..2..1..2 %e A205757 ..2..1..1..2..1....1..1..1..2..0....0..0..2..2..0....0..2..0..2..1 %K A205757 nonn %O A205757 1,1 %A A205757 _R. H. Hardin_ Jan 30 2012