Differences between A061075 and A005422 or A003020

[all at abouthugo.de]

"Pfoertner, Hugo" <Hugo.Pfoertner at muc.mtu.de> schrieb am 18.03.2003,
12:20:31:
> 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,...)?
                           ^^^^ typo
> Can anyone extend it?

I did that myself,

the definition is not very elegant :-( 

Primes p such that p divides 10^n-1, p is the largest prime
producing fraction period n and p is not the largest prime
dividing 10^n-1.

13, 52579, 8779, 2161, 69857, 909090909090909091, 459691,
549797184491917, 14175966169,
which correspond with decimal fraction periods
6,   18,    22,   30,    32,          38,            42,
      46,            54,

Please check.
 
Thanks
Hugo Pfoertner