Numbers that require exactly five chisel strokes when written in Roman numerals.

Terms

a(0) =8a(1) =13a(2) =14a(3) =16a(4) =19a(5) =21a(6) =41a(7) =53a(8) =54a(9) =56a(10) =59a(11) =61a(12) =91a(13) =103a(14) =104a(15) =106a(16) =109a(17) =111a(18) =151a(19) =201a(20) =400a(21) =502a(22) =505a(23) =510a(24) =550a(25) =600a(26) =1001a(27) =5002a(28) =5005a(29) =5010