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 A278626 #4 Nov 24 2016 08:46:01 %S A278626 504,103546,24103803,6594175430,1892563134910,540194658701142, %T A278626 152561415660718514,42854095125044269456,11909803616605399424974, %U A278626 3223604568067184016119193,835430834890906525681829626 %N A278626 Number of nX7 0..2 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly one mistake. %C A278626 Column 7 of A278627. %H A278626 R. H. Hardin, <a href="/A278626/b278626.txt">Table of n, a(n) for n = 1..19</a> %e A278626 Some solutions for n=2 %e A278626 ..2..0..1..1..1..0..0. .0..2..2..2..2..1..1. .2..2..1..1..0..1..0 %e A278626 ..2..1..2..2..2..2..2. .0..2..2..2..2..2..0. .2..2..2..0..2..1..1 %Y A278626 Cf. A278627. %K A278626 nonn %O A278626 1,1 %A A278626 _R. H. Hardin_, Nov 24 2016