Phi(n) + 6 | sigma(n + 6).

Terms

a(0) =9a(1) =18a(2) =20a(3) =27a(4) =28a(5) =52a(6) =54a(7) =68a(8) =76a(9) =81a(10) =104a(11) =116a(12) =126a(13) =130a(14) =162a(15) =172a(16) =188a(17) =212a(18) =228a(19) =243a(20) =258a(21) =268a(22) =292a(23) =350a(24) =356a(25) =362a(26) =388a(27) =452a(28) =486a(29) =508