Number of permutations of 1..n with i-10<=p(i)<=i+4.

Terms

a(0) =1a(1) =2a(2) =6a(3) =24a(4) =120a(5) =600a(6) =3000a(7) =15000a(8) =75000a(9) =375000a(10) =1875000a(11) =8981784a(12) =42195774a(13) =197451926a(14) =929043391a(15) =4418144281a(16) =21115063084a(17) =101076625300a(18) =483821382744