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 A214009 #6 Jun 02 2025 08:05:02 %S A214009 6,756,2663506,269462676001,807203255071567008 %N A214009 Number of n X n nonnegative integer matrices with row and column i=1..n having sum <= i*5. %C A214009 Column 5 of A214011 %e A214009 Some solutions for n=3 %e A214009 ..2..0..0....1..0..0....0..0..5....0..0..0....0..0..0....4..0..0....0..0..3 %e A214009 ..0..9..1....0..8..0....0..0..0....0..1..9....0..4..0....0..0..8....0..0..0 %e A214009 ..0..0..9....0..1..1....0..4..9....1..7..2....0..6..0....0..1..1....0..6..4 %K A214009 nonn %O A214009 1,1 %A A214009 _R. H. Hardin_ Jun 30 2012