a(n) = A000043(n) written in base 4.

Terms

a(0) =2a(1) =3a(2) =11a(3) =13a(4) =31a(5) =101a(6) =103a(7) =133a(8) =331a(9) =1121a(10) =1223a(11) =1333a(12) =20021a(13) =21133a(14) =103333a(15) =202123a(16) =203221a(17) =302101a(18) =1002131a(19) =1011013a(20) =2113121a(21) =2123111a(22) =2233031a(23) =10313201a(24) =11103011a(25) =11222221a(26) =22313101a(27) =111003203a(28) =122332213a(29) =200033101