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 A214006 #6 Jun 02 2025 08:04:41 %S A214006 3,54,7722,9318805,98721672541,9463992096711104,8396505064286814402888 %N A214006 Number of n X n nonnegative integer matrices with row and column i=1..n having sum <= i*2. %C A214006 Column 2 of A214011 %e A214006 Some solutions for n=3 %e A214006 ..0..2..0....0..0..0....2..0..0....2..0..0....0..0..0....0..0..0....0..0..1 %e A214006 ..0..0..0....0..0..4....0..1..0....0..0..2....0..1..0....0..4..0....0..0..3 %e A214006 ..0..0..5....0..1..0....0..0..0....0..1..2....0..2..0....1..0..1....0..3..0 %K A214006 nonn %O A214006 1,1 %A A214006 _R. H. Hardin_ Jun 30 2012