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Primes p such that p divides 10^n-1, p is the largest prime producing decimal fraction period n and p is not the largest prime dividing 10^n-1.
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%I #18 Apr 27 2022 20:46:40

%S 13,52579,8779,2161,69857,909090909090909091,459691,549797184491917,

%T 14175966169,183411838171,296557347313446299,388847808493,

%U 3404193829806058997303,8985695684401,297262705009139006771611927

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

%H Max Alekseyev, <a href="/A081317/b081317.txt">Table of n, a(n) for n = 1..54</a> (first 50 terms from Ray Chandler)

%H Sam Wagstaff, The Cunningham Project, <a href="http://www.cerias.purdue.edu/homes/ssw/cun/">The Main Tables</a>

%F Numbers in A061075(n) such that A061075(n) is not equal to A005422(n). The corresponding values of n are given in A081318.

%F a(n) = A061075(A081318(n)). - _Max Alekseyev_, Apr 27 2022

%e a(1)=13 because the largest factor 37 in the factorization of 10^6-1=999999=3^3*7*11*13*37 already occurs in the factorization of 10^3-1=3^3*37 and produces only a decimal fraction period of 3. 1/37=0.027027027...., 1/13=0.0769230769230...

%Y Cf. A005422, A003020, A061075, A081318.

%K nonn,base

%O 1,1

%A _Hugo Pfoertner_, Mar 18 2003

%E More terms from _Hans Havermann_, May 31 2003