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 A074907 #13 Mar 28 2020 10:14:11 %S A074907 570,870,1290,1878,1890,3870,6426,10854,13830,19434,20886,21606,25098, %T A074907 26742,26754,40446,63234,77406,110754,171486,253458,295740,647748, %U A074907 1077612,1467588,1956812,2109796,1889486,953914,668966,353578,176792 %N A074907 Aliquot sequence starting at 570. %D A074907 R. K. Guy, Unsolved Problems in Number Theory, B6. %H A074907 R. J. Mathar, <a href="/A074907/b074907.txt">Table of n, a(n) for n = 0..173</a> %H A074907 Christophe CLAVIER, <a href="http://christophe.clavier.free.fr/Aliquot/site/Aliquot.html">Aliquot Sequences</a> %F A074907 a(n+1) = A001065(a(n)). - _R. J. Mathar_, Oct 11 2017 %e A074907 a(0) = 570, a(1) = sigma(570) - 570 = 870. %t A074907 FixedPointList[If[# > 0, DivisorSigma[1, #] - #, 0]&, 570] // Most (* _Jean-François Alcover_, Mar 28 2020 *) %Y A074907 Cf. A008888, A008889. %K A074907 nonn,fini,full %O A074907 0,1 %A A074907 Robert A. Stump (bee_ess107(AT)msn.com), Sep 30 2002