Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,2,1.

A037537

Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,2,1.

Terms

    a(0) =1a(1) =6a(2) =25a(3) =101a(4) =406a(5) =1625a(6) =6501a(7) =26006a(8) =104025a(9) =416101a(10) =1664406a(11) =6657625a(12) =26630501a(13) =106522006a(14) =426088025a(15) =1704352101a(16) =6817408406a(17) =27269633625a(18) =109078534501a(19) =436314138006

External references