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 A202631 #8 Jul 22 2025 16:43:54 %S A202631 4,184,143028,1960824272,443471777729100 %N A202631 Number of n X n 0..3 arrays with adjacent row and column sums unequal. %C A202631 Diagonal of A202636 %e A202631 Some solutions for n=3 %e A202631 ..2..0..3....0..1..0....0..1..0....2..3..2....2..0..0....0..2..3....3..2..1 %e A202631 ..1..0..3....1..3..1....2..0..0....3..0..2....3..2..3....2..2..2....2..2..3 %e A202631 ..0..2..0....2..0..0....2..2..2....3..2..2....2..2..0....0..0..2....1..0..1 %K A202631 nonn %O A202631 1,1 %A A202631 _R. H. Hardin_ Dec 21 2011