a(n) = A142458(n, 1 + floor(n/2)).

Terms

a(0) =1a(1) =1a(2) =8a(3) =39a(4) =546a(5) =5482a(6) =109640a(7) =1709675a(8) =44451550a(9) =947113254a(10) =30307624128a(11) =821539580358