Maximal base 7 run length is 4.

Terms

a(0) =400a(1) =800a(2) =1200a(3) =1600a(4) =2000a(5) =2400a(6) =2401a(7) =2800a(8) =2802a(9) =2803a(10) =2804a(11) =2805a(12) =2806a(13) =3201a(14) =3601a(15) =4001a(16) =4401a(17) =4801a(18) =4802a(19) =5202a(20) =5600a(21) =5601a(22) =5603a(23) =5604a(24) =5605a(25) =5606a(26) =6002a(27) =6402a(28) =6802a(29) =7202