Smallest natural number requiring n letters in Spanish.

Terms

a(0) =1a(1) =3a(2) =5a(3) =4a(4) =14a(5) =40a(6) =16a(7) =17a(8) =25a(9) =24a(10) =35a(11) =34a(12) =44a(13) =54a(14) =125a(15) =124a(16) =135a(17) =134a(18) =144a(19) =154a(20) =235a(21) =234a(22) =244a(23) =254a(24) =354a(25) =444a(26) =454a(27) =1354a(28) =1444a(29) =1454