Number of permutations of 1..n with i-9<=p(i)<=i+5.

Terms

a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =720a(6) =4320a(7) =25920a(8) =155520a(9) =933120a(10) =5223720a(11) =28065624a(12) =148043310a(13) =779305142a(14) =4138663683a(15) =22326100565a(16) =121438789028a(17) =662769584476