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 A278733 #5 Nov 28 2021 12:38:30 %S A278733 2472,3633649,7907770636,19983433877142,50067074390669892, %T A278733 119979123054325787300,276347089984710259199248, %U A278733 616342267580395469193910007 %N A278733 Number of n X 7 0..3 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly one mistake. %C A278733 Column 7 of A278734. %e A278733 Some solutions for n=1 %e A278733 ..2..2..0..2..2..1..0. .2..0..0..0..0..0..1. .3..2..2..1..1..0..2 %Y A278733 Cf. A278734. %K A278733 nonn %O A278733 1,1 %A A278733 _R. H. Hardin_, Nov 27 2016