Numbers that contain only one nonzero digit.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =7a(7) =8a(8) =9a(9) =10a(10) =20a(11) =30a(12) =40a(13) =50a(14) =60a(15) =70a(16) =80a(17) =90a(18) =100a(19) =200a(20) =300a(21) =400a(22) =500a(23) =600a(24) =700a(25) =800a(26) =900a(27) =1000a(28) =2000a(29) =3000