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 A263368 #4 Oct 16 2015 07:30:34 %S A263368 2,7,82,865,9888,107514,1260442,15048493,180640864,2167406803, %T A263368 26004426192,311958557356,3743219626994,44918305209517, %U A263368 539021844275470,6468267502547329,77619174191856096,931428840572850954 %N A263368 Number of (n+1)X(3+1) 0..2 arrays with each row and column divisible by 7, read as a base-3 number with top and left being the most significant digits. %C A263368 Column 3 of A263373. %H A263368 R. H. Hardin, <a href="/A263368/b263368.txt">Table of n, a(n) for n = 1..210</a> %e A263368 Some solutions for n=4 %e A263368 ..1..2..1..1....2..2..1..2....0..0..0..0....0..0..2..1....2..1..2..1 %e A263368 ..2..2..1..2....0..0..0..0....1..0..2..2....0..2..1..0....1..2..1..1 %e A263368 ..1..0..0..1....1..2..1..1....0..0..0..0....2..0..0..2....1..0..0..1 %e A263368 ..1..2..1..1....1..0..0..1....0..0..0..0....1..0..2..2....1..1..2..0 %e A263368 ..0..2..1..0....1..2..1..1....1..0..2..2....0..2..1..0....2..2..1..2 %Y A263368 Cf. A263373. %K A263368 nonn %O A263368 1,1 %A A263368 _R. H. Hardin_, Oct 16 2015