Position of n-th 3 in A030604.

Terms

a(0) =3a(1) =9a(2) =10a(3) =14a(4) =35a(5) =37a(6) =48a(7) =57a(8) =66a(9) =70a(10) =83a(11) =84a(12) =90a(13) =91a(14) =99a(15) =110a(16) =142a(17) =143a(18) =146a(19) =147a(20) =149a(21) =153a(22) =160a(23) =166a(24) =191a(25) =194a(26) =197a(27) =204a(28) =206a(29) =216