Numbers consisting of either 2's and 0's or 5's and 0's.

Terms

a(0) =2a(1) =5a(2) =20a(3) =50a(4) =200a(5) =202a(6) =220a(7) =500a(8) =505a(9) =550a(10) =2000a(11) =2002a(12) =2020a(13) =2022a(14) =2200a(15) =2202a(16) =2220a(17) =5000a(18) =5005a(19) =5050a(20) =5055a(21) =5500a(22) =5505a(23) =5550a(24) =20000a(25) =20002a(26) =20020a(27) =20022a(28) =20200a(29) =20202