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 A205411 #7 Jul 22 2025 18:50:41 %S A205411 236576,5686031,151598017,2839359056,67792717447,1715387177450, %T A205411 36803297869771,858554973465776,20804813475950945,468182020666807407, %U A205411 10859505355533459702,257344051938542231086,5904014034167014999764 %N A205411 Number of (n+2)X6 0..2 arrays with every 3X3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly two ways, and new values 0..2 introduced in row major order. %C A205411 Column 4 of A205415 %H A205411 R. H. Hardin, <a href="/A205411/b205411.txt">Table of n, a(n) for n = 1..88</a> %e A205411 Some solutions for n=3 %e A205411 ..0..1..2..0..2..2....0..1..2..2..1..0....0..1..0..2..1..2....0..0..0..1..0..1 %e A205411 ..1..2..2..0..0..0....2..0..2..0..2..2....2..1..1..1..1..2....1..2..1..1..1..1 %e A205411 ..2..2..2..0..0..1....2..2..2..2..2..2....1..1..1..2..1..2....1..1..1..1..2..2 %e A205411 ..2..0..2..2..0..1....2..0..0..0..0..2....0..2..1..2..2..2....1..0..2..1..2..1 %e A205411 ..0..0..2..2..0..0....2..2..0..1..1..2....1..0..1..1..1..1....0..0..0..1..1..1 %K A205411 nonn %O A205411 1,1 %A A205411 _R. H. Hardin_ Jan 26 2012