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 A278433 #4 Nov 22 2016 06:54:26 %S A278433 456,178352,67971132,23450120081,7817299555828,2573951428892959, %T A278433 803631265741510560,228568783548126804702,58279844921391047673160, %U A278433 13321187192307993333262298,2747056699156070175271175528 %N A278433 Number of nX5 0..3 arrays with rows and columns in lexicographic nondecreasing order but with exactly one mistake. %C A278433 Column 5 of A278435. %H A278433 R. H. Hardin, <a href="/A278433/b278433.txt">Table of n, a(n) for n = 1..50</a> %e A278433 Some solutions for n=2 %e A278433 ..0..0..1..1..1. .0..1..0..0..3. .0..0..1..2..0. .0..3..0..0..1 %e A278433 ..0..2..0..3..1. .0..3..0..0..2. .2..2..0..2..2. .1..3..1..3..1 %Y A278433 Cf. A278435. %K A278433 nonn %O A278433 1,1 %A A278433 _R. H. Hardin_, Nov 22 2016