First column of A027516.

Terms

a(0) =1a(1) =3a(2) =11a(3) =38a(4) =316a(5) =3183a(6) =11265a(7) =14759a(8) =17862a(9) =22567a(10) =107889a(11) =136101a(12) =8146735a(13) =180468251a(14) =431027647a(15) =523109219a(16) =309378032a(17) =747071157a(18) =6153823083a(19) =139774726451a(20) =164308335281