Number of permutations of length n within distance 8.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =24a(5) =120a(6) =720a(7) =5040a(8) =40320a(9) =362880a(10) =2943360a(11) =21898800a(12) =152622000a(13) =1017952680a(14) =6623303544a(15) =42700751022a(16) =276054834902