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 A061075 #33 Nov 25 2024 19:16:18
%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 8779,11111111111111111111111,99990001,182521213001,1058313049,440334654777631,121499449,77843839397
%N A061075 Greatest prime number p(n) with decimal fraction period of length n.
%H A061075 <a href="/A061075/b061075.txt">Table of n, a(n) for n = 1..352</a>
%H A061075 Makoto Kamada, <a href="https://stdkmd.net/nrr/repunit/phin10.htm">Factorizations of Phi_n(10)</a>
%H A061075 <a href="/index/1#1overn">Index entries for sequences related to decimal expansion of 1/n</a>
%F A061075 a(n) = A006530(A019328(n)). - _Ray Chandler_, May 10 2017
%e A061075 1/271 = 0.0036900369, period of n=5 for p(5)=271.
%t A061075 a[n_] := Cyclotomic[n, 10] // FactorInteger // Last // First; Table[a[n], {n, 1, 26}] (* _Jean-François Alcover_, Aug 05 2013, after Pari *)
%o A061075 (PARI) a(n) = my(p); if(n<1, 0, p=factor(polcyclo(n,10))[,1]; p[#p])
%Y A061075 Cf. A003020, A005422, A006530, A007138, A019328.
%Y A061075 Last terms in rows of A046107.
%K A061075 nonn,nice,base
%O A061075 1,1
%A A061075 Heiner Muller-Merbach (hmm(AT)sozwi.uni-kl.de), May 29 2001
%E A061075 Terms to a(322) in b-file from _Ray Chandler_, Apr 28 2017
%E A061075 a(323)-a(352) in b-file from _Max Alekseyev_, Apr 26 2022