a(1) = 1, and for n > 1, a(n) = A005940(1+sigma(A156552(n))).

Terms

a(0) =1a(1) =2a(2) =4a(3) =5a(4) =8a(5) =9a(6) =16a(7) =7a(8) =25a(9) =18a(10) =32a(11) =25a(12) =64a(13) =21a(14) =21a(15) =49a(16) =128a(17) =27a(18) =256a(19) =35a(20) =40a(21) =121a(22) =512a(23) =49a(24) =125a(25) =385a(26) =49a(27) =121a(28) =1024a(29) =13