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 A330429 #10 Mar 01 2020 08:15:37 %S A330429 9,15,1005079920836,13695542245376,26160864154416,27402841561095, %T A330429 27599063056565,110263115897935,124632211478775,127400054266476, %U A330429 154090744843026,205849483744896,231019991767556,339938754880725,459718637643265,632733228632505,646552697065275,683008674773416,884965354448175 %N A330429 Numbers k such that phi(k) = phi(k+9), where phi (A000010) is Euler's totient function. %C A330429 a(20) > 10^15. %H A330429 Kevin Ford, <a href="https://arxiv.org/abs/2002.12155">Solutions of phi(n)=phi(n+k) and sigma(n)=sigma(n+k)</a>, arXiv:2002.12155 [math.NT], 2020. %H A330429 S. W. Graham, J. J. Holt, and C. Pomerance, <a href="https://math.dartmouth.edu/~carlp/phi.pdf">On the solutions to phi(n) = phi(n+k)</a>, Number Theory in Progress, K. Gyory, H. Iwaniec, and J. Urbanowicz, eds., vol. 2, de Gruyter, Berlin and New York, 1999, pp. 867-882. %Y A330429 Cf. A000010, A007015. %Y A330429 Cf. A001274, A001494, A330251, A179186, A179187, A179188, A179189, A179202. %Y A330429 Cf. A276503, A276504, A217139. %K A330429 nonn %O A330429 1,1 %A A330429 _Giovanni Resta_, Mar 01 2020