Partial sums of repdigits of A002281.

Terms

a(0) =0a(1) =7a(2) =84a(3) =861a(4) =8638a(5) =86415a(6) =864192a(7) =8641969a(8) =86419746a(9) =864197523a(10) =8641975300a(11) =86419753077a(12) =864197530854