Partial sums of A004977.

Terms

a(0) =1a(1) =3a(2) =6a(3) =11a(4) =19a(5) =29a(6) =42a(7) =58a(8) =81a(9) =113a(10) =157a(11) =213a(12) =289a(13) =391a(14) =523a(15) =697a(16) =924a(17) =1220a(18) =1603a(19) =2108a(20) =2787a(21) =3679a(22) =4830a(23) =6346a(24) =8334a(25) =10936a(26) =14336a(27) =18746a(28) =24505a(29) =32024