Number of non-isomorphic twice-balanced multiset partitions of weight n.

Terms

a(0) =1a(1) =1a(2) =0a(3) =2a(4) =3a(5) =6a(6) =20a(7) =65a(8) =134a(9) =482a(10) =1562a(11) =4974a(12) =15466a(13) =51768a(14) =179055a(15) =631737a(16) =2216757a(17) =7905325a(18) =28768472a(19) =106852116a(20) =402255207a(21) =1532029660a(22) =5902839974a(23) =23041880550a(24) =91129833143a(25) =364957188701