If n = Product (p_j^k_j) then a(n) = Sum (p_j^k_j) (a(1) = 0 by convention).

Terms

a(0) =0a(1) =2a(2) =3a(3) =4a(4) =5a(5) =5a(6) =7a(7) =8a(8) =9a(9) =7a(10) =11a(11) =7a(12) =13a(13) =9a(14) =8a(15) =16a(16) =17a(17) =11a(18) =19a(19) =9a(20) =10a(21) =13a(22) =23a(23) =11a(24) =25a(25) =15a(26) =27a(27) =11a(28) =29a(29) =10