Exactly 3 digits from {1,2,3,4,5,6,7,8,9} can precede a(n) to form a lucky number.

Terms

a(0) =1a(1) =5a(2) =7a(3) =11a(4) =15a(5) =21a(6) =23a(7) =33a(8) =37a(9) =39a(10) =51a(11) =59a(12) =61a(13) =67a(14) =73a(15) =77a(16) =79a(17) =89a(18) =91a(19) =95a(20) =97a(21) =107a(22) =111a(23) =115a(24) =121a(25) =127a(26) =139a(27) =151a(28) =163a(29) =175