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 A082072 #21 Nov 06 2017 02:49:36
%S A082072 1,1,2,7,2,2,2,5,13,2,2,2,2,2,2,31,2,13,2,2,2,2,2,2,31,2,2,2,2,2,2,3,
%T A082072 2,2,2,7,2,2,2,2,2,2,2,2,2,2,2,2,3,3,2,2,2,2,2,2,2,2,2,2,2,2,2,127,2,
%U A082072 2,2,2,2,2,2,5,2,2,2,2,2,2,2,2,11,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,2,7,2,2
%N A082072 Smallest prime that divides sigma(n) = A000203(n) and sigma_2(n) = A001157(n), or 1 if sigma(n) and sigma_2(n) are relatively prime.
%H A082072 Antti Karttunen, <a href="/A082072/b082072.txt">Table of n, a(n) for n = 1..16384</a>
%F A082072 a(n) = A020639(A179931(n)). - _Antti Karttunen_, Nov 03 2017
%t A082072 ffi[x_] := Flatten[FactorInteger[x]]; lf[x_] := Length[FactorInteger[x]]; ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}]; f1[x_] := DivisorSigma[1, x]; f2[x_] := DivisorSigma[2, x]; Table[Min[Intersection[ba[f1[w]], ba[f2[w]]]], {w, 1, 128}]
%t A082072 (* Second program: *)
%t A082072 Array[If[CoprimeQ[#1, #2], 1, Min@ Apply[Intersection, Map[FactorInteger[#][[All, 1]] &, {#1, #2}]]] & @@ {DivisorSigma[1, #], DivisorSigma[2, #]} &, 105] (* _Michael De Vlieger_, Nov 03 2017 *)
%o A082072 (PARI) lpf(n)=my(f=factor(n)[,1]); if(#f,f[1],1)
%o A082072 a(n)=lpf(gcd(sigma(n),sigma(n,2))) \\ _Charles R Greathouse IV_, Feb 14 2013
%Y A082072 Cf. A000203, A001157, A020639, A179931.
%Y A082072 Cf. also A082066, A082067, A082068, A082069, A082070, A082071.
%K A082072 nonn
%O A082072 1,3
%A A082072 _Labos Elemer_, Apr 07 2003
%E A082072 Name edited by _Antti Karttunen_ after an example by _N. J. A. Sloane_, Nov 04 2017