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 A230186 #6 Jun 02 2025 08:42:37 %S A230186 0,33,231,3411,44487,596973,7957785,106248147,1418070843,18928121865, %T A230186 252644742093,3372208415751,45010959441111,600789299156241, %U A230186 8019108619691037,107036033204372163,1428676544542445175 %N A230186 Number of 3Xn 0..2 arrays x(i,j) with each element horizontally or antidiagonally next to at least one element with value 2-x(i,j). %C A230186 Row 3 of A230184 %H A230186 R. H. Hardin, <a href="/A230186/b230186.txt">Table of n, a(n) for n = 1..210</a> %F A230186 Empirical: a(n) = 9*a(n-1) +59*a(n-2) +17*a(n-3) -361*a(n-4) -569*a(n-5) +530*a(n-6) +2304*a(n-7) +1442*a(n-8) -3272*a(n-9) -5911*a(n-10) -927*a(n-11) +5899*a(n-12) +3415*a(n-13) +293*a(n-14) -3915*a(n-15) -688*a(n-16) +770*a(n-17) +146*a(n-18) +984*a(n-19) -112*a(n-20) +176*a(n-21) for n>23 %e A230186 Some solutions for n=3 %e A230186 ..2..0..2....0..2..1....2..0..2....1..1..1....0..2..0....1..1..2....0..2..2 %e A230186 ..2..1..1....0..1..1....2..1..0....2..0..1....2..0..0....2..0..1....2..0..2 %e A230186 ..0..2..0....1..0..2....1..2..0....2..1..1....0..2..0....1..1..1....2..1..1 %K A230186 nonn %O A230186 1,2 %A A230186 _R. H. Hardin_, Oct 11 2013