Partial sums of A009927.

Terms

a(0) =1a(1) =13a(2) =63a(3) =183a(4) =401a(5) =745a(6) =1291a(7) =2019a(8) =2921a(9) =4133a(10) =5659a(11) =7443a(12) =9597a(13) =12149a(14) =15103a(15) =18535a(16) =22389a(17) =26729a(18) =31727a(19) =37231a(20) =43233a(21) =50001a(22) =57443a(23) =65467a(24) =74281a(25) =83853a(26) =94187a(27) =105419a(28) =117397a(29) =130221