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 A230201 #21 Jun 07 2019 23:47:48 %S A230201 2,4,6,8,10,12,14,16,18,20,22,24,30,32,34,36,40,42,44,46,48,50,54,58, %T A230201 60,64,66,68,70,72,78,80,84,90,92,94,96,98,100,102,106,108,110,114, %U A230201 118,120,126,128,130,132,136,138,140,144,150,156,160,162,166,168 %N A230201 Numbers k such that sigma(phi(k)) < k. %C A230201 All terms are even. However, sigma(phi(k)) may be equal to k for an odd number k if k+2 is a Fermat prime. %H A230201 Robert Israel, <a href="/A230201/b230201.txt">Table of n, a(n) for n = 1..10000</a> %p A230201 for n do if sigma(phi(n))<n then print{n} fi od: %t A230201 Select[Range[200], DivisorSigma[1, EulerPhi[#]] < # &] (* _T. D. Noe_, Oct 14 2013 *) %o A230201 (PARI) isok(n) = sigma(eulerphi(n)) < n; \\ _Michel Marcus_, Oct 12 2013 %Y A230201 Cf. A000010, A000203, A001229, A018784, A062402, A066694, A227011, A227927, A230203. %K A230201 nonn %O A230201 1,1 %A A230201 _Vladimir Letsko_, Oct 11 2013