Number of permutations of 1..n with i-7<=p(i)<=i+5.

Terms

a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =720a(6) =4320a(7) =25920a(8) =140520a(9) =714264a(10) =3519294a(11) =17234438a(12) =85314915a(13) =431525429a(14) =2206564916a(15) =11325792940a(16) =58101677088a(17) =297290799936