Third column of A162170.

Terms

a(0) =1a(1) =3a(2) =6a(3) =20a(4) =75a(5) =336a(6) =1708a(7) =9792a(8) =62325a(9) =436480a(10) =3334386a(11) =27595776a(12) =245951615a(13) =2348666880a(14) =23923317720a(15) =258910994432