Sum of numbers of bipartite partitions of (n,k) into distinct pairs for 0<=k<=n.

Terms

a(0) =1a(1) =3a(2) =9a(3) =33a(4) =96a(5) =273a(6) =749a(7) =1953a(8) =4916a(9) =12023a(10) =28642a(11) =66575a(12) =151544a(13) =338294a(14) =741880a(15) =1601048a(16) =3403936a(17) =7137386a(18) =14774713a(19) =30219025a(20) =61115184a(21) =122300146a(22) =242312186a(23) =475589389a(24) =925158391a(25) =1784529840a(26) =3414565313a(27) =6483608230a(28) =12221370425a(29) =22876263089