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 A165630 #10 Jun 20 2021 18:48:41 %S A165630 8721,10179,21489,99813,203721,228417,229653,250705,268047,609957, %T A165630 1150713,1343277,2429283,2835417,2835807,2881197,3150333,3230469, %U A165630 3833181,4679157,4885569,5673291,6082527,6302529,6713637,6819879,7096329,9464121,10313979,12168651 %N A165630 Numbers n such that sigma(n)/phi(n) = 25/9, where sigma = A000203, phi = A000010. %C A165630 A subsequence of A011257. Contains the product m*n of relatively prime (gcd(m,n)=1) terms (m,n) in A164647 x A164648. %H A165630 Donovan Johnson, <a href="/A165630/b165630.txt">Table of n, a(n) for n = 1..1000</a> %t A165630 Select[Range[122*10^5],DivisorSigma[1,#]/EulerPhi[#]==25/9&] (* _Harvey P. Dale_, Jun 20 2021 *) %o A165630 (PARI) for( i=1,1e7, sigma(i)/eulerphi(i)==25/9 && print1(i", ")) %K A165630 nonn %O A165630 1,1 %A A165630 _Farideh Firoozbakht_ and _M. F. Hasler_, Sep 23 2009