a(n) = Sum_{p|n, p prime} sigma_p(p).

Terms

a(0) =0a(1) =5a(2) =28a(3) =5a(4) =3126a(5) =33a(6) =823544a(7) =5a(8) =28a(9) =3131a(10) =285311670612a(11) =33a(13) =823549a(14) =3154a(15) =5a(17) =33a(19) =3131a(20) =823572a(21) =285311670617a(23) =33a(24) =3126