Duplicate of A099920.

Terms

a(0) =0a(1) =0a(2) =2a(3) =3a(4) =8a(5) =15a(6) =30a(7) =56a(8) =104a(9) =189a(10) =340a(11) =605a(12) =1068a(13) =1872a(14) =3262a(15) =5655a(16) =9760a(17) =16779