Position of n-th 3 in A030413.

Terms

a(0) =3a(1) =8a(2) =16a(3) =18a(4) =27a(5) =33a(6) =41a(7) =42a(8) =45a(9) =49a(10) =50a(11) =70a(12) =75a(13) =85a(14) =86a(15) =89a(16) =90a(17) =91a(18) =92a(19) =96a(20) =113a(21) =118a(22) =122a(23) =123a(24) =124a(25) =125a(26) =132a(27) =137a(28) =139a(29) =141