Position of n-th 3 in A030373.

Terms

a(0) =3a(1) =11a(2) =19a(3) =20a(4) =22a(5) =24a(6) =26a(7) =27a(8) =39a(9) =51a(10) =63a(11) =65a(12) =68a(13) =71a(14) =74a(15) =75a(16) =87a(17) =99a(18) =111a(19) =113a(20) =116a(21) =119a(22) =122a(23) =123a(24) =124a(25) =127a(26) =130a(27) =133a(28) =135a(29) =136