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 A278308 #4 Nov 17 2016 07:07:43 %S A278308 504,197981,114457714,69684770828,38819080346585,20065923383306483, %T A278308 10174217016822816668,5193800251722254864596, %U A278308 2618709455820562585030428,1260058503482337718156082135,564882872428920086722942207177 %N A278308 Number of nX7 0..2 arrays with rows and columns in lexicographic nondecreasing order but with exactly one mistake. %C A278308 Column 7 of A278309. %H A278308 R. H. Hardin, <a href="/A278308/b278308.txt">Table of n, a(n) for n = 1..19</a> %e A278308 Some solutions for n=2 %e A278308 ..0..0..0..2..0..0..0. .0..0..0..1..1..2..0. .0..0..0..1..1..0..1 %e A278308 ..0..1..2..2..0..0..0. .1..1..1..1..1..0..0. .0..2..2..0..1..0..0 %Y A278308 Cf. A278309. %K A278308 nonn %O A278308 1,1 %A A278308 _R. H. Hardin_, Nov 17 2016