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 A065818 #25 Dec 30 2024 12:51:17
%S A065818 5,119,3553,4147,8323,198679,218569,248501,298129,468809,547261,
%T A065818 1098349,1398061,1947379,1990417,3076549,3453289,3994753,6969529,
%U A065818 7690249,8790439,11905457,13097327,14346577,14732011,14988967,15286973,16145269,20851493,21622867,23083081,24924599,26218777,26326867
%N A065818 Numbers k such that 3*phi(k) = 2*sigma(k).
%H A065818 Jud McCranie, <a href="/A065818/b065818.txt">Table of n, a(n) for n = 1..10000</a> (first 75 terms from Harry J. Smith)
%e A065818 n = 3553, 3*phi(3553) = 8640 = 2*4320 = 2*sigma(3553).
%t A065818 Select[Range[20000000], 3EulerPhi[#] == 2DivisorSigma[1, #] &] (* _Harvey P. Dale_, Apr 18 2011 *)
%o A065818 (PARI) isok(k) = { 3*eulerphi(k) == 2*sigma(k) } \\ _Harry J. Smith_, Oct 31 2009
%Y A065818 Cf. A000010, A000203, A062699, A065819.
%K A065818 nonn
%O A065818 1,1
%A A065818 _Labos Elemer_, Nov 23 2001
%E A065818 a(22)-a(28) from _Harry J. Smith_, Oct 31 2009