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 A278432 #4 Nov 22 2016 06:53:35 %S A278432 155,19624,2116789,223202074,23450120081,2266913897519, %T A278432 191704868748703,14075699487073288,906324694033572285, %U A278432 51875514109305962403,2672849198449587976472,125300087299510807859757 %N A278432 Number of nX4 0..3 arrays with rows and columns in lexicographic nondecreasing order but with exactly one mistake. %C A278432 Column 4 of A278435. %H A278432 R. H. Hardin, <a href="/A278432/b278432.txt">Table of n, a(n) for n = 1..132</a> %e A278432 Some solutions for n=2 %e A278432 ..0..0..1..3. .1..3..1..1. .0..1..3..3. .1..3..3..3. .1..0..0..1 %e A278432 ..3..1..3..2. .3..1..0..2. .3..0..3..2. .0..3..3..3. .3..0..2..0 %Y A278432 Cf. A278435. %K A278432 nonn %O A278432 1,1 %A A278432 _R. H. Hardin_, Nov 22 2016