This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A081317 #18 Apr 27 2022 20:46:40 %S A081317 13,52579,8779,2161,69857,909090909090909091,459691,549797184491917, %T A081317 14175966169,183411838171,296557347313446299,388847808493, %U A081317 3404193829806058997303,8985695684401,297262705009139006771611927 %N A081317 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 A081317 Max Alekseyev, <a href="/A081317/b081317.txt">Table of n, a(n) for n = 1..54</a> (first 50 terms from Ray Chandler) %H A081317 Sam Wagstaff, The Cunningham Project, <a href="http://www.cerias.purdue.edu/homes/ssw/cun/">The Main Tables</a> %F A081317 Numbers in A061075(n) such that A061075(n) is not equal to A005422(n). The corresponding values of n are given in A081318. %F A081317 a(n) = A061075(A081318(n)). - _Max Alekseyev_, Apr 27 2022 %e A081317 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 A081317 Cf. A005422, A003020, A061075, A081318. %K A081317 nonn,base %O A081317 1,1 %A A081317 _Hugo Pfoertner_, Mar 18 2003 %E A081317 More terms from _Hans Havermann_, May 31 2003