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 A067065 #27 May 15 2025 00:44:43
%S A067065 20,26,41,44,65,83,132,133,140,182,188,195,249,287,299,420,546,564,
%T A067065 620,644,764,806,861,897,1001,1115,1169,1271,28644,32172,35052,39116,
%U A067065 40796,41478,42315,47492,50162,51513,52143,53745,54033,54483,56427,56642
%N A067065 Numbers k such that sigma(sigma(sigma(k))) == 6*sigma(k).
%H A067065 Amiram Eldar, <a href="/A067065/b067065.txt">Table of n, a(n) for n = 1..270</a> (terms 1..146 from Harry J. Smith)
%t A067065 Select[Range[60000],Nest[DivisorSigma[1,#]&,#,3]==6*DivisorSigma[1,#]&] (* _Harvey P. Dale_, Oct 04 2016 *)
%o A067065 (PARI) isok(k) = { sigma(sigma(sigma(k))) == 6*sigma(k) } \\ _Harry J. Smith_, May 03 2010
%Y A067065 Cf. A000203 (sigma), A066971.
%K A067065 nonn
%O A067065 1,1
%A A067065 _Benoit Cloitre_, Feb 17 2002
%E A067065 Definition corrected and more terms added by _Harry J. Smith_, May 03 2010