Partial sums of A005109.

Terms

a(0) =2a(1) =5a(2) =10a(3) =17a(4) =30a(5) =47a(6) =66a(7) =103a(8) =176a(9) =273a(10) =382a(11) =545a(12) =738a(13) =995a(14) =1428a(15) =1915a(16) =2492a(17) =3261a(18) =4414a(19) =5711a(20) =7170a(21) =9763a(22) =12680a(23) =16137a(24) =20026a(25) =30395a(26) =42684a(27) =60181a(28) =78614a(29) =117981