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 A322688 #23 Jan 15 2019 17:27:13 %S A322688 568,638,1824,1836,3051,3219,4185,4389,4960,5236,6368,6764,7749,8151, %T A322688 9184,9724,9760,11050,11032,12470,11176,12586,13420,14350,15169,15265, %U A322688 17376,19206,18788,20150,23848,26866,26355,27962,26784,29260,28809,30381,30199,30217,32128,33128,32940,37050,34144,36244,37592,39795 %N A322688 Two-column table read by rows: Primitive distinct pairs that have the same value of phi, sigma, and tau. %C A322688 The terms are consecutive pairs, ordered so that (A) a(2i-1) < a(2i) for i > 0, and (B) a(2i+1) < a(2i+3) for i >= 0. This sequence has primitive solutions only. If k is relatively prime to all of the terms in a primitive pair, then multiplying the terms in that pair by k gives another solution - see A134922. In Burton's book (see references), problem 3 in section 7.2 asks the reader to prove a special case for (568,638). %D A322688 David Burton, Elementary Number Theory, 4th edition, 1998, section 7.2. %H A322688 Jud McCranie, <a href="/A322688/b322688.txt">Table of n, a(n) for n = 1..10000</a> %e A322688 phi(568)=phi(638)=280; sigma(568)=sigma(638)=1080; tau(568)=tau(638)=8. %Y A322688 Cf. A134922, A322687, A322689, A322690, A322691, A322692, A322693, A322694, A322695, A322696, A322696. %K A322688 nonn,tabf %O A322688 1,1 %A A322688 _Jud McCranie_, Dec 31 2018