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 A223783 #7 Jul 23 2025 04:30:30 %S A223783 3,81,8635,1560013,343454446,82093381460,20229461153969, %T A223783 5020313112266183 %N A223783 Number of n X n 0..2 arrays with rows, diagonals and antidiagonals unimodal. %C A223783 Diagonal of A223789 %e A223783 Some solutions for n=3 %e A223783 ..2..1..1....0..1..1....0..2..1....0..0..2....0..0..0....2..1..0....0..0..1 %e A223783 ..1..1..1....0..2..0....2..1..0....0..1..1....0..1..1....1..1..0....0..2..2 %e A223783 ..0..1..1....2..2..1....0..2..1....0..2..2....2..1..0....2..1..0....2..1..0 %K A223783 nonn %O A223783 1,1 %A A223783 _R. H. Hardin_ Mar 27 2013