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 A233156 #8 Oct 09 2018 14:56:44 %S A233156 27,96,432,1944,8856,40392,184248,840456,3833784,17488008,79772472, %T A233156 363886344,1659886776,7571661192,34538532408,157549339656, %U A233156 718669633464,3278249488008,14953908173112,68213041889544,311157393101496 %N A233156 Number of 3 X n 0..2 arrays with no element x(i,j) adjacent to value 2-x(i,j) horizontally or antidiagonally. %H A233156 R. H. Hardin, <a href="/A233156/b233156.txt">Table of n, a(n) for n = 1..210</a> %F A233156 Empirical: a(n) = 5*a(n-1) - 2*a(n-2) for n>4. %F A233156 Empirical g.f.: 3*x*(9 - 13*x + 2*x^2 - 8*x^3) / (1 - 5*x + 2*x^2). - _Colin Barker_, Oct 09 2018 %e A233156 Some solutions for n=5: %e A233156 ..1..0..0..0..1....1..0..1..0..1....0..0..0..1..2....0..1..0..0..1 %e A233156 ..0..0..0..0..1....0..0..1..0..1....0..1..2..2..2....0..0..1..0..1 %e A233156 ..0..0..1..0..1....1..2..1..0..1....0..1..2..2..2....0..0..0..0..1 %Y A233156 Row 3 of A233155. %K A233156 nonn %O A233156 1,1 %A A233156 _R. H. Hardin_, Dec 05 2013