a(1) = 1; a(n+1) = n + Sum_{d|n} a(d).

Terms

a(0) =1a(1) =2a(2) =5a(3) =9a(4) =16a(5) =22a(6) =36a(7) =44a(8) =64a(9) =79a(10) =108a(11) =120a(12) =171a(13) =185a(14) =238a(15) =275a(16) =347a(17) =365a(18) =477a(19) =497a(20) =624a(21) =687a(22) =820a(23) =844a(24) =1071a(25) =1113a(26) =1313a(27) =1410a(28) =1671a(29) =1701