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 A221248 #5 Jun 26 2022 02:44:24 %S A221248 0,441,21660,4096576,438377904,56606878084,6757282699788, %T A221248 830820670081600,100904384322992160 %N A221248 Number of 4 X n arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor. %C A221248 Row 4 of A221245. %e A221248 Some solutions for n=3 %e A221248 ..0..1..0....0..3..0....0..0..1....0..0..0....0..3..0....2..1..0....0..1..0 %e A221248 ..1..1..1....0..2..1....1..4..0....2..6..0....0..2..1....0..5..0....2..3..1 %e A221248 ..0..5..0....1..0..1....1..4..0....1..2..0....1..1..0....0..1..0....1..1..0 %e A221248 ..1..1..1....0..3..1....0..0..1....1..0..0....2..2..0....0..1..2....0..3..0 %Y A221248 Cf. A221245. %K A221248 nonn %O A221248 1,2 %A A221248 _R. H. Hardin_, Jan 06 2013