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 A278318 #6 Apr 21 2020 12:52:03 %S A278318 0,3,236,19854,3058990,1133034160,1159826452573,3539023342110534, %T A278318 33693644340398789900,1032075934040317150939325 %N A278318 Number of n X n 0..1 arrays with rows and columns in lexicographic nondecreasing order but with exactly two mistakes. %C A278318 Diagonal of A278325. %e A278318 Some solutions for n=4 %e A278318 ..0..1..0..0. .0..1..0..1. .0..0..1..0. .0..0..1..0. .0..0..1..1 %e A278318 ..0..1..0..0. .1..0..0..1. .0..1..1..0. .0..0..0..0. .1..1..0..0 %e A278318 ..0..0..1..1. .0..0..0..0. .1..0..1..0. .0..1..0..1. .1..1..0..1 %e A278318 ..1..0..0..1. .0..1..0..0. .0..1..0..1. .1..0..0..1. .1..0..0..0 %Y A278318 Cf. A278325. %K A278318 nonn %O A278318 1,2 %A A278318 _R. H. Hardin_, Nov 18 2016