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 A209458 #10 Jul 22 2025 21:43:51 %S A209458 1,6,2027,26142922,9920302864598,61881181615562063430 %N A209458 Number of n X n 0..6 arrays with every 2X2 subblock containing exactly one value repeat, and new values 0..6 introduced in row major order. %C A209458 Diagonal of A209465 %e A209458 Some.solutions.for.n=4 %e A209458 ..0..0..1..0....0..0..1..0....0..1..0..0....0..0..1..0....0..0..0..0 %e A209458 ..1..2..0..2....1..2..0..3....0..2..1..2....1..2..0..2....1..2..1..2 %e A209458 ..3..2..1..1....0..0..1..0....0..1..3..1....1..3..3..0....0..2..3..1 %e A209458 ..0..2..3..4....1..2..0..2....0..2..2..2....0..0..1..0....0..1..1..4 %K A209458 nonn %O A209458 1,2 %A A209458 _R. H. Hardin_ Mar 09 2012