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 A379639 #13 Feb 27 2025 11:05:45
%S A379639 5,7,43,37,311,31,55987,1297,19,11,23,13,3433,29,1171,17,239,46441,
%T A379639 191,241,1822428931,51828151,47,1678321,18198701,53,163,421,
%U A379639 7369130657357778596659,1950271,5333,353,67,190537,71,73,149,1787,3143401,41,8648131,2527867231
%N A379639 Smallest primitive prime factor of 6^n-1.
%C A379639 Also, smallest prime p such that 1/p has senary period n.
%H A379639 Max Alekseyev, <a href="/A379639/b379639.txt">Table of n, a(n) for n = 1..436</a> (first 420 terms from Sean A. Irvine)
%o A379639 (PARI) listap(nn) = {prf = []; for (n=1, nn, vp = (factor(6^n-1)[, 1])~; f = setminus(Set(vp), Set(prf)); prf = concat(prf, f); print1(vecmin(Vec(f)), ", "); ); }
%Y A379639 Cf. A112927 (base 2), A143663 (base 3), A112092 (base 4), A143665 (base 5), A379639 (base 6), A379640 (base 7), A379641 (base 8), A379642 (base 9), A007138 (base 10), A379644 (base 11), A252170 (base 12).
%Y A379639 Cf. A274907.
%K A379639 nonn
%O A379639 1,1
%A A379639 _Sean A. Irvine_, Dec 28 2024