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 A214007 #6 Jun 02 2025 08:04:48 %S A214007 4,160,85639,641631566,69768979161580,113333423255541329550 %N A214007 Number of n X n nonnegative integer matrices with row and column i=1..n having sum <= i*3. %C A214007 Column 3 of A214011 %e A214007 Some solutions for n=3 %e A214007 ..0..0..0....0..0..0....2..0..0....0..0..1....0..0..0....1..0..0....3..0..0 %e A214007 ..3..0..0....0..2..0....0..1..0....0..0..1....0..2..0....0..0..4....0..0..1 %e A214007 ..0..4..0....0..0..3....1..2..0....0..6..0....3..0..1....0..6..0....0..1..7 %K A214007 nonn %O A214007 1,1 %A A214007 _R. H. Hardin_ Jun 30 2012