Numbers with no 0's in base-4 expansion.

Terms

a(0) =1a(1) =2a(2) =3a(3) =5a(4) =6a(5) =7a(6) =9a(7) =10a(8) =11a(9) =13a(10) =14a(11) =15a(12) =21a(13) =22a(14) =23a(15) =25a(16) =26a(17) =27a(18) =29a(19) =30a(20) =31a(21) =37a(22) =38a(23) =39a(24) =41a(25) =42a(26) =43a(27) =45a(28) =46a(29) =47