Urban numbers: without 'r' or 'u'.

Terms

a(0) =1a(1) =2a(2) =5a(3) =6a(4) =7a(5) =8a(6) =9a(7) =10a(8) =11a(9) =12a(10) =15a(11) =16a(12) =17a(13) =18a(14) =19a(15) =20a(16) =21a(17) =22a(18) =25a(19) =26a(20) =27a(21) =28a(22) =29a(23) =50a(24) =51a(25) =52a(26) =55a(27) =56a(28) =57a(29) =58