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 A263820 #7 Jun 02 2025 12:15:22 %S A263820 450,134028,21876416,3019386508,469723808009,74221751084228, %T A263820 11527528524302048,1793121938656927984 %N A263820 Number of (4+1)X(n+1) arrays of permutations of 0..n*5+4 with each element having index change (+-,+-) 0,0 0,1 0,2 or 1,0. %C A263820 Row 4 of A263816 %e A263820 Some solutions for n=2 %e A263820 ..2..4..1....0..4..2....0..2..1....0..4..2....0..2..1....2..0..1....2..0..1 %e A263820 ..0..7..5....3..1..5....6..7..3....6..1..3....4..7..8....3..5..8....3..4..5 %e A263820 ..3..6..8....7..8..6....8..4..5....8..7..5....3..6..5....6..4..7....7..8..6 %e A263820 ..9.11.10....9.11.14....9.10.14...12.13.11...11..9.14...12.13.11...10.11..9 %e A263820 .12.13.14...12.10.13...12.13.11....9.10.14...12.10.13....9.10.14...12.14.13 %Y A263820 Cf. A263816 %K A263820 nonn %O A263820 1,1 %A A263820 _R. H. Hardin_, Oct 27 2015