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 A278777 #4 Nov 28 2016 08:22:35 %S A278777 56,5209,189595,5355983,141166787,3634987413,90752836672, %T A278777 2155380363189,48042054699217,999491681597761,19416161058987737, %U A278777 353517442918850559,6065787121333416262,98680235108923294584,1531317900358396738494 %N A278777 Number of nX7 0..1 arrays with rows in nondecreasing lexicographic order and columns in nonincreasing lexicographic order, but with exactly two mistakes. %C A278777 Column 7 of A278778. %H A278777 R. H. Hardin, <a href="/A278777/b278777.txt">Table of n, a(n) for n = 1..81</a> %e A278777 Some solutions for n=3 %e A278777 ..1..0..1..1..0..0..0. .0..0..0..1..1..1..1. .1..1..0..0..1..0..0 %e A278777 ..1..0..0..0..1..0..0. .0..1..0..1..0..0..0. .0..0..1..0..0..1..0 %e A278777 ..1..0..0..0..1..0..0. .0..1..1..0..1..0..0. .1..1..0..1..0..0..1 %Y A278777 Cf. A278778. %K A278777 nonn %O A278777 1,1 %A A278777 _R. H. Hardin_, Nov 28 2016