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 A206234 #8 Jun 14 2018 09:32:29 %S A206234 1640,5728,27168,283728,1236432,9042600,95322432,419146392,3065437344, %T A206234 32314300392,142090622832,1039183255560,10954547828832,48168721135992, %U A206234 352283123630784,3713591713969992,16329196465097232,119423978910831720 %N A206234 Number of (n+1) X 5 0..3 arrays with every 2 X 3 or 3 X 2 subblock having exactly two equal edges, and new values 0..3 introduced in row major order. %C A206234 Column 4 of A206238. %H A206234 R. H. Hardin, <a href="/A206234/b206234.txt">Table of n, a(n) for n = 1..210</a> %F A206234 Empirical: a(n) = a(n-1) + 339*a(n-3) - 339*a(n-4) for n>8. %F A206234 Empirical g.f.: 8*x*(205 + 511*x + 2680*x^2 - 37425*x^3 - 54141*x^4 + 67251*x^5 - 86751*x^6 + 107163*x^7) / ((1 - x)*(1 - 339*x^3)). - _Colin Barker_, Jun 14 2018 %e A206234 Some solutions for n=4: %e A206234 ..0..0..1..1..2....0..0..1..2..0....0..0..1..1..2....0..1..0..0..2 %e A206234 ..1..1..2..1..1....0..3..2..2..0....1..1..2..1..1....2..0..0..3..0 %e A206234 ..2..1..1..2..1....3..2..2..0..1....3..1..1..2..1....0..0..1..0..0 %e A206234 ..3..0..1..1..2....2..2..3..1..1....1..2..1..1..2....3..3..0..0..3 %e A206234 ..3..3..2..1..2....2..3..1..1..0....1..1..2..1..1....1..3..0..1..2 %Y A206234 Cf. A206238. %K A206234 nonn %O A206234 1,1 %A A206234 _R. H. Hardin_, Feb 05 2012