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 A229842 #6 Jun 02 2025 08:38:49 %S A229842 3,81,987,13401,178311,2381469,31783299,424240833,5662582239, %T A229842 75582071565,1008840783171,13465626160209,179734091085543, %U A229842 2399022766771749,32021249796760479,427407548197383945,5704874525707845543 %N A229842 Number of nX3 0..2 arrays x(i,j) with each element horizontally or vertically next to at least one element with value 2-x(i,j). %C A229842 Column 3 of A229847 %H A229842 R. H. Hardin, <a href="/A229842/b229842.txt">Table of n, a(n) for n = 1..210</a> %F A229842 Empirical: a(n) = 10*a(n-1) +44*a(n-2) +20*a(n-3) -122*a(n-4) -303*a(n-5) -129*a(n-6) +244*a(n-7) +526*a(n-8) -74*a(n-9) -220*a(n-10) -225*a(n-11) +96*a(n-12) +172*a(n-13) -50*a(n-14) +44*a(n-15) %e A229842 Some solutions for n=3 %e A229842 ..2..0..1....1..1..1....1..2..0....2..0..2....1..2..2....2..2..0....1..1..0 %e A229842 ..1..1..1....2..0..0....1..1..1....1..0..2....1..0..0....0..1..0....1..2..2 %e A229842 ..2..0..1....0..2..2....1..0..2....1..1..0....1..2..2....1..1..2....2..0..2 %K A229842 nonn %O A229842 1,1 %A A229842 _R. H. Hardin_, Oct 01 2013