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 A229869 #6 Jul 23 2025 05:48:12 %S A229869 6,216,143856,2805425280,1656812779036416,30688414550520167402496 %N A229869 Number of n X n 0..5 arrays with corresponding row and column sums equal. %C A229869 Column 5 of A229870 %e A229869 Some solutions for n=4 %e A229869 ..0..0..3..3....0..3..0..3....0..3..3..0....0..3..3..3....0..0..3..3 %e A229869 ..3..0..3..0....3..0..0..0....3..0..0..3....3..0..3..3....3..0..0..3 %e A229869 ..1..4..2..5....1..0..2..4....2..1..0..3....2..2..3..2....2..4..3..1 %e A229869 ..2..2..4..2....2..0..5..5....1..2..3..0....4..4..0..1....1..2..4..0 %K A229869 nonn %O A229869 1,1 %A A229869 _R. H. Hardin_, Oct 01 2013