Partial sums of A001605.

Terms

a(0) =3a(1) =7a(2) =12a(3) =19a(4) =30a(5) =43a(6) =60a(7) =83a(8) =112a(9) =155a(10) =202a(11) =285a(12) =416a(13) =553a(14) =912a(15) =1343a(16) =1776a(17) =2225a(18) =2734a(19) =3303a(20) =3874a(21) =6845a(22) =11568a(23) =16955a(24) =26266a(25) =35943a(26) =50374a(27) =75935a(28) =106692a(29) =142691