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 A081397 #14 Aug 28 2019 10:25:29
%S A081397 3,14,488,16072,284229,29221621,25014312576
%N A081397 a(n) = least k such that GCD of sigma(k) = A000203(k) and phi(k) = A000010(k) equals n-th primorial = A002110(n).
%C A081397 a(8) <= 1524139588224. - _Donovan Johnson_, Dec 14 2009
%F A081397 a(n) = Min_{k : A081396(k) = A002110(n)}.
%e A081397 k=284229: sigma(284229) = 482790 = 2*3*5*7*11*19, phi(284229) = 166320 = 2*2*2*3*3*3*3*5*7*11, common factor set = {2,3,5,7,11}, gcd(sigma,phi) = 2310.
%Y A081397 Cf. A000010, A000203, A002110, A081383, A081396.
%K A081397 nonn,more
%O A081397 1,1
%A A081397 _Labos Elemer_, Mar 28 2003
%E A081397 a(6) corrected and a(7) from _Donovan Johnson_, Dec 14 2009