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 A213958 #6 Jun 02 2025 08:04:21 %S A213958 5,275,199735,1839121115,214090209950060,314911377440218697950, %T A213958 5858129386840205449108592935 %N A213958 Number of n X n 0..4 matrices with row and column i=1..n having sum <= i*4. %C A213958 Column 4 of A213962 %e A213958 Some solutions for n=4 %e A213958 ..2..0..2..0....2..0..0..0....1..3..0..0....3..0..0..0....2..1..0..1 %e A213958 ..1..3..4..0....2..2..3..0....0..4..2..1....0..4..1..3....0..1..4..1 %e A213958 ..0..1..0..3....0..2..2..3....0..1..0..1....0..2..1..1....0..4..3..4 %e A213958 ..0..3..4..0....0..2..2..0....1..0..4..0....0..2..4..2....0..0..1..0 %K A213958 nonn %O A213958 1,1 %A A213958 _R. H. Hardin_ Jun 28 2012