Number of permutations of 1..n with i-9<=p(i)<=i+6.

Terms

a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =720a(6) =5040a(7) =35280a(8) =246960a(9) =1728720a(10) =11167920a(11) =68286120a(12) =404423736a(13) =2363607402a(14) =13821281314a(15) =81653389147a(16) =490572457453