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 A268157 #7 Apr 12 2023 08:08:53 %S A268157 0,1,8,36,456,6360,93600,1784160,38102400,899579520,23960966400, %T A268157 699741504000 %N A268157 Number of n X 3 arrays containing 3 copies of 0..n-1 with every element equal to at least one vertical or antidiagonal neighbor and the top left element equal to 0. %C A268157 Column 3 of A268159. %e A268157 Some solutions for n=4 %e A268157 ..0..0..2....0..0..1....0..0..2....0..0..2....0..1..1....0..0..1....0..3..3 %e A268157 ..0..1..2....0..1..2....0..2..1....0..2..3....0..1..3....0..1..3....0..3..1 %e A268157 ..1..2..3....1..3..2....2..1..3....2..1..3....0..3..2....1..3..2....0..2..1 %e A268157 ..1..3..3....3..3..2....1..3..3....1..1..3....3..2..2....3..2..2....2..2..1 %Y A268157 Cf. A268159. %K A268157 nonn %O A268157 1,3 %A A268157 _R. H. Hardin_, Jan 27 2016