Smallest number with derivative n.

Terms

a(0) =0a(1) =2a(2) =4a(3) =5a(4) =8a(5) =9a(6) =11a(7) =10a(8) =16a(9) =17a(10) =19a(11) =18a(12) =23a(13) =22a(14) =20a(15) =21a(16) =32a(17) =33a(18) =35a(19) =34a(20) =39a(21) =38a(22) =36a(23) =37a(24) =47a(25) =46a(26) =44a(27) =45a(28) =40a(29) =41