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 A224117 #6 Jun 02 2025 08:30:24 %S A224117 0,1,27,282,2050,12405,67557,344708,1686132,8017335,37383775, %T A224117 171917790,782635542,3535573769,15875062665,70921483080,315457366696 %N A224117 Number of idempotent n X n 0..1 matrices of rank n-2. %C A224117 Column 1 of A224118 %e A224117 Some solutions for n=3 %e A224117 ..0..0..0....1..0..0....0..0..0....0..0..1....0..0..0....1..0..0....0..0..0 %e A224117 ..1..1..0....0..0..0....0..1..0....0..0..1....0..0..0....1..0..0....1..0..1 %e A224117 ..0..0..0....0..0..0....0..1..0....0..0..1....1..0..1....1..0..0....1..0..1 %K A224117 nonn %O A224117 1,3 %A A224117 _R. H. Hardin_ Apr 09 2013