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 A263591 #4 Oct 22 2015 12:40:18 %S A263591 1,2,6,16,52,208,800,3360,16224,78088,393408,2189872,12371616, %T A263591 71835000,448860480,2871278464,18727425440,129070035784,913845701344 %N A263591 Number of length n arrays of permutations of 0..n-1 with each element moved by -n to n places and the median of every three consecutive elements nondecreasing. %C A263591 Diagonal of A263597. %e A263591 Some solutions for n=6 %e A263591 ..0....0....5....4....0....4....4....4....1....5....2....3....1....0....0....4 %e A263591 ..1....3....0....2....2....2....1....0....2....2....0....1....2....5....3....1 %e A263591 ..2....2....2....0....5....1....0....1....4....1....4....2....0....2....2....0 %e A263591 ..3....1....3....5....3....5....2....3....0....3....3....4....3....1....4....5 %e A263591 ..4....4....1....3....1....3....3....5....3....4....1....5....4....3....5....2 %e A263591 ..5....5....4....1....4....0....5....2....5....0....5....0....5....4....1....3 %Y A263591 Cf. A263597. %K A263591 nonn %O A263591 1,2 %A A263591 _R. H. Hardin_, Oct 22 2015