a(n) = A078252(n)/n.

Terms

a(0) =1a(1) =5a(2) =37a(3) =303a(4) =10101a(5) =16835a(6) =1010101a(7) =2020202a(8) =12345679a(9) =101010101a(10) =2662993572a(11) =10101010101a(12) =0a(16) =0a(18) =0