a(n) = 1 + (a(n-1) interpreted as a hexadecimal number); a(1)=1.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =5a(5) =6a(6) =7a(7) =8a(8) =9a(9) =10a(10) =17a(11) =24a(12) =37a(13) =56a(14) =87a(15) =136a(16) =311a(17) =786a(18) =1927a(19) =6440a(20) =25665a(21) =153190a(22) =1388945a(23) =20482374a(24) =541598581a(25) =22571222402