Digit '4' concatenated with a(n) is a lucky number.

Terms

a(0) =3a(1) =9a(2) =15a(3) =21a(4) =27a(5) =29a(6) =33a(7) =51a(8) =63a(9) =75a(10) =77a(11) =83a(12) =87a(13) =89a(14) =95a(15) =105a(16) =107a(17) =129a(18) =131a(19) =161a(20) =165a(21) =173a(22) =179a(23) =189a(24) =195a(25) =201a(26) =203a(27) =207a(28) =227a(29) =237