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 A278306 #4 Nov 17 2016 07:05:56 %S A278306 126,11486,986014,79562696,6345491150,507575149862,38819080346585, %T A278306 2710823731820118,169682177514345615,9515799841809545361, %U A278306 481274130722917682825,22134553939263522315031,933117878015049935514941 %N A278306 Number of nX5 0..2 arrays with rows and columns in lexicographic nondecreasing order but with exactly one mistake. %C A278306 Column 5 of A278309. %H A278306 R. H. Hardin, <a href="/A278306/b278306.txt">Table of n, a(n) for n = 1..99</a> %e A278306 Some solutions for n=2 %e A278306 ..0..2..2..0..2. .1..2..2..1..2. .0..0..1..1..2. .0..0..1..0..2 %e A278306 ..1..0..2..2..1. .2..1..2..2..2. .0..0..0..0..0. .0..2..2..1..0 %Y A278306 Cf. A278309. %K A278306 nonn %O A278306 1,1 %A A278306 _R. H. Hardin_, Nov 17 2016