Number of permutations p of [n] such that max_{j=1..n} |p(j)-j| = floor(n/2).

A323807

Number of permutations p of [n] such that max_{j=1..n} |p(j)-j| = floor(n/2).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =9a(4) =23a(5) =157a(6) =503a(7) =4833a(8) =18827a(9) =234061a(10) =1076807a(11) =16447329a(12) =87358763a(13) =1583571277a(14) =9541763303a(15) =200258110593

External references