Third column of A027516.

Terms

a(0) =2a(1) =8a(2) =121a(3) =1508a(4) =7032a(5) =10541a(6) =15648a(7) =21965a(8) =121510a(9) =167546a(10) =11264974a(11) =270029270a(12) =708365875a(13) =921551651a(14) =591592617a(15) =1519648505a(16) =13442945149a(17) =323054346341a(18) =404363551947