Numbers k such that k surrounded by digit '7' is a lucky number.

Terms

a(0) =1a(1) =2a(2) =7a(3) =8a(4) =16a(5) =19a(6) =20a(7) =23a(8) =35a(9) =37a(10) =43a(11) =44a(12) =50a(13) =56a(14) =67a(15) =68a(16) =71a(17) =73a(18) =82a(19) =83a(20) =89a(21) =91a(22) =94a(23) =101a(24) =103a(25) =104a(26) =115a(27) =127a(28) =134a(29) =151