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 A224120 #5 Jun 02 2025 08:30:45 %S A224120 12405,260235,2273505,12775065,52968495,178881705,514370175, %T A224120 1311704565,3033506835,6484756785 %N A224120 Number of idempotent 6X6 0..n matrices of rank 4. %C A224120 Row 6 of A224118 %e A224120 Some solutions for n=3 %e A224120 ..0..0..3..0..0..0....1..0..1..1..0..0....1..0..0..0..1..0....1..0..0..0..0..0 %e A224120 ..0..1..0..0..0..0....0..1..1..1..0..0....0..1..0..0..1..0....0..1..0..0..0..0 %e A224120 ..0..0..1..0..0..0....0..0..0..0..0..0....0..0..1..0..0..0....0..0..1..0..0..0 %e A224120 ..0..0..0..1..0..0....0..0..0..0..0..0....3..0..2..0..3..0....2..1..0..0..0..3 %e A224120 ..0..0..0..0..0..0....0..0..3..1..1..0....0..0..0..0..0..0....0..0..2..0..0..1 %e A224120 ..0..0..0..0..1..1....0..0..1..0..0..1....0..0..0..0..0..1....0..0..0..0..0..1 %K A224120 nonn %O A224120 1,1 %A A224120 _R. H. Hardin_ Apr 09 2013