Position of n-th 3 in A030588.

Terms

a(0) =2a(1) =7a(2) =13a(3) =16a(4) =18a(5) =19a(6) =20a(7) =25a(8) =31a(9) =39a(10) =48a(11) =57a(12) =62a(13) =65a(14) =66a(15) =68a(16) =75a(17) =84a(18) =93a(19) =102a(20) =111a(21) =116a(22) =119a(23) =120a(24) =122a(25) =129a(26) =138a(27) =142a(28) =145a(29) =147