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 A323807 #7 Jan 28 2019 19:14:24
%S A323807 1,1,2,9,23,157,503,4833,18827,234061,1076807,16447329,87358763,
%T A323807 1583571277,9541763303,200258110593,1350025656107,32202026068621,
%U A323807 240183024181127,6418149695049249,52479230675397803,1553052337531253197,13814973114258788903,448537638127408597953,4312466658317635366187
%N A323807 Number of permutations p of [n] such that max_{j=1..n} |p(j)-j| = floor(n/2).
%F A323807 a(n) = A130152(n,floor(n/2)).
%e A323807 a(4) = 9: 1342, 1423, 1432, 2314, 2413, 3124, 3142, 3214, 3412.
%e A323807 a(5) = 23: 12453, 12534, 12543, 13425, 13524, 14235, 14253, 14325, 14523, 21453, 21534, 21543, 23145, 23154, 24135, 24153, 31245, 31254, 31425, 31524, 32145, 32154, 34125.
%Y A323807 Cf. A130152.
%K A323807 nonn
%O A323807 1,3
%A A323807 _Alois P. Heinz_, Jan 28 2019