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 A205469 #7 Jul 22 2025 18:54:38 %S A205469 48,263,1548,9654,61978,405702,2686876,17926060,120146998,807610262, %T A205469 5438698312,36669657896,247432193154,1670424338586,11280890946852, %U A205469 76200323465372,514795456961870,3478208969481038,23502035785763264 %N A205469 Number of (n+1)X3 0..2 arrays with every 2X2 subblock having the same number of equal edges, and new values 0..2 introduced in row major order. %C A205469 Column 2 of A205475 %H A205469 R. H. Hardin, <a href="/A205469/b205469.txt">Table of n, a(n) for n = 1..210</a> %F A205469 Empirical: a(n) = 16*a(n-1) -85*a(n-2) +142*a(n-3) +159*a(n-4) -676*a(n-5) +465*a(n-6) +298*a(n-7) -506*a(n-8) +220*a(n-9) -32*a(n-10) %e A205469 Some solutions for n=4 %e A205469 ..0..0..1....0..1..0....0..1..2....0..0..0....0..0..0....0..1..0....0..1..0 %e A205469 ..1..2..1....1..2..1....1..2..0....0..1..0....0..1..0....0..1..0....0..1..0 %e A205469 ..1..0..0....2..1..2....2..1..2....1..1..1....1..1..0....0..0..0....0..0..0 %e A205469 ..1..2..1....0..2..0....0..2..1....2..1..0....2..1..0....1..0..1....2..0..2 %e A205469 ..1..0..0....1..0..1....1..0..2....2..1..1....2..1..1....1..1..1....2..0..2 %K A205469 nonn %O A205469 1,1 %A A205469 _R. H. Hardin_ Jan 27 2012