Self-stuffable numbers (see the Comments section for definition).

Terms

a(0) =20a(1) =22a(2) =120a(3) =126a(4) =300a(5) =2200a(6) =4000a(7) =50000a(8) =150000a(9) =202020a(10) =231000a(11) =240000a(12) =600000a(13) =1600000a(14) =2500000a(15) =7000000a(16) =12500000a(17) =14300000a(18) =40400000a(19) =44000000a(20) =80000000a(21) =101250000a(22) =102600000a(23) =108000000a(24) =112500000a(25) =120120120a(26) =126000000a(27) =131400000a(28) =144000000a(29) =180000000