Position of n-th 3 in A030401.

Terms

a(0) =2a(1) =6a(2) =10a(3) =11a(4) =13a(5) =14a(6) =20a(7) =26a(8) =32a(9) =34a(10) =37a(11) =38a(12) =44a(13) =50a(14) =56a(15) =58a(16) =61a(17) =62a(18) =63a(19) =66a(20) =68a(21) =69a(22) =72a(23) =74a(24) =75a(25) =78a(26) =80a(27) =81a(28) =82a(29) =84