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 A266133 #4 Dec 21 2015 12:30:51 %S A266133 1,20,77,117,278,1959,11044,36730,123887,598383,2919993,11429093, %T A266133 43919671,194434626,880889564,3627851352,14690154222,63196827262, %U A266133 276336307138,1159331148853,4807640087709,20468995961561,88006303609494 %N A266133 Number of 3Xn integer arrays with each element equal to the number of horizontal, diagonal and antidiagonal neighbors exactly one smaller than itself. %C A266133 Row 3 of A266131. %H A266133 R. H. Hardin, <a href="/A266133/b266133.txt">Table of n, a(n) for n = 1..210</a> %H A266133 R. H. Hardin, <a href="/A266133/a266133.txt">Empirical recurrence of order 77</a> %F A266133 Empirical recurrence of order 77 (see link above) %e A266133 Some solutions for n=4 %e A266133 ..1..1..1..1....1..2..0..0....2..1..1..2....1..2..0..1....2..1..2..0 %e A266133 ..1..0..0..2....1..0..0..0....0..1..1..0....1..0..2..0....1..1..0..0 %e A266133 ..0..2..1..1....1..1..2..1....2..1..1..2....1..1..0..0....1..0..2..1 %Y A266133 Cf. A266131. %K A266133 nonn %O A266133 1,2 %A A266133 _R. H. Hardin_, Dec 21 2015