Differences between A061075 and A005422 or A003020

[Pfoertner, Hugo]

SeqFans,

is the sequence of differences between

%I A005422 M2889
%S A005422 3,11,37,101,271,_37_,4649,137,333667,9091,513239,9901,265371653,
%T A005422
909091,2906161,5882353,5363222357,_333667_,1111111111111111111,27961,1083868
9,
%U A003020 _513239_,11111111111111111111111,99990001,182521213001
%N A005422 Largest factor of 10^n -1.

BTW, A005422 and A003020 are identical with the exception of the additional
first term.

and

%I A061075
%S A061075
3,11,37,101,271,_13_,4649,137,333667,9091,513239,9901,265371653,909091,
%T A061075
2906161,5882353,5363222357,_52579_,1111111111111111111,27961,10838689,
%U A061075 _8779_,11111111111111111111111
%N A061075 Greatest prime number p(n) with decimal fraction period of length
n.

an infinite sequence (13,5279,8779,...)?
Can anyone extend it?

Regards
Hugo Pfoertner