a(n) = tau(n)^2, where tau(n) = A000005(n).

Terms

a(0) =1a(1) =4a(2) =4a(3) =9a(4) =4a(5) =16a(6) =4a(7) =16a(8) =9a(9) =16a(10) =4a(11) =36a(12) =4a(13) =16a(14) =16a(15) =25a(16) =4a(17) =36a(18) =4a(19) =36a(20) =16a(21) =16a(22) =4a(23) =64a(24) =9a(25) =16a(26) =16a(27) =36a(28) =4a(29) =64