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 A278378 #6 Apr 21 2020 12:53:19 %S A278378 0,0,74,23640,8632118,6204309386,11105331450864,55821544343692020, %T A278378 843729327193891754770,40033544602806238643588014 %N A278378 Number of n X n 0..1 arrays with rows and columns in lexicographic nondecreasing order but with exactly three mistakes. %C A278378 Diagonal of A278385. %e A278378 Some solutions for n=4 %e A278378 ..1..1..0..0. .0..1..0..0. .1..1..1..1. .1..0..1..1. .1..1..0..1 %e A278378 ..0..0..0..1. .1..1..1..0. .1..1..1..0. .0..0..1..1. .0..0..1..0 %e A278378 ..0..0..0..0. .1..1..0..0. .0..0..0..0. .1..0..1..1. .0..1..1..1 %e A278378 ..1..1..0..1. .1..1..0..0. .0..0..1..1. .0..0..0..1. .0..1..0..0 %Y A278378 Cf. A278385. %K A278378 nonn %O A278378 1,3 %A A278378 _R. H. Hardin_, Nov 20 2016