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 A231850 #8 Oct 01 2018 09:35:23 %S A231850 3,34,656,12404,234336,4426924,83630516,1579892344,29846280396, %T A231850 563836173564,10651619780176,201223350436284,3801378343993156, %U A231850 71813123491132504,1356645994919661436,25628858153744306924 %N A231850 Number of n X 3 0..2 arrays with no element having a strict majority of its horizontal and antidiagonal neighbors equal to itself plus one mod 3, with upper left element zero (rock paper and scissors drawn positions). %H A231850 R. H. Hardin, <a href="/A231850/b231850.txt">Table of n, a(n) for n = 1..210</a> %F A231850 Empirical: a(n) = 21*a(n-1) - 41*a(n-2) + 22*a(n-3) for n>4. %F A231850 Empirical g.f.: x*(3 - 29*x + 65*x^2 - 44*x^3) / (1 - 21*x + 41*x^2 - 22*x^3). - _Colin Barker_, Oct 01 2018 %e A231850 Some solutions for n=5: %e A231850 ..0..0..1....0..0..1....0..0..1....0..0..2....0..0..2....0..0..0....0..0..0 %e A231850 ..0..2..2....0..1..2....0..1..2....0..2..1....0..2..2....1..1..0....1..2..2 %e A231850 ..0..2..2....0..2..0....0..2..1....0..1..1....2..0..1....0..2..2....0..2..2 %e A231850 ..0..1..2....2..0..1....2..0..1....2..0..2....1..1..0....1..0..0....2..0..1 %e A231850 ..0..0..1....1..2..2....2..2..2....2..2..0....1..0..0....1..0..0....0..2..2 %Y A231850 Column 3 of A231855. %K A231850 nonn %O A231850 1,1 %A A231850 _R. H. Hardin_, Nov 14 2013