Loxton-van der Poorten sequence: base-4 representation contains only -1, 0, +1.

Terms

a(0) =0a(1) =1a(2) =3a(3) =4a(4) =5a(5) =11a(6) =12a(7) =13a(8) =15a(9) =16a(10) =17a(11) =19a(12) =20a(13) =21a(14) =43a(15) =44a(16) =45a(17) =47a(18) =48a(19) =49a(20) =51a(21) =52a(22) =53a(23) =59a(24) =60a(25) =61a(26) =63a(27) =64a(28) =65a(29) =67