Number of permutations of 1..n with i-6<=p(i)<=i+5.

Terms

a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =720a(6) =4320a(7) =22920a(8) =112056a(9) =525642a(10) =2441314a(11) =11467387a(12) =55213453a(13) =269051424a(14) =1315752712a(15) =6425315520a(16) =31265476224a(17) =151611449472a(18) =733893891840