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 A019291 #38 Dec 27 2021 21:07:06 %S A019291 217728,1278720,2983680,5621760,14008320,298721280,955367424, %T A019291 1874780160,4874428416,1957928934528 %N A019291 Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (2,14)-perfect numbers. %C A019291 See also the Cohen-te Riele links under A019276. %C A019291 No other terms < 5*10^11. - _Jud McCranie_, Feb 08 2012 %C A019291 36095341363200 is also a term. See comment in A019278. - _Michel Marcus_, May 15 2016 %C A019291 a(11) > 4*10^12. - _Giovanni Resta_, Feb 26 2020 %H A019291 Graeme L. Cohen and Herman J. J. te Riele, <a href="http://projecteuclid.org/euclid.em/1047565640">Iterating the sum-of-divisors function</a>, Experimental Mathematics, 5 (1996), pp. 93-100. %o A019291 (PARI) isok(n) = sigma(sigma(n))/n == 14; \\ _Michel Marcus_, May 15 2016 %Y A019291 Cf. A019276, A019278, A019279, A019281, A019282, A019283, A019284, A019285, A019286, A019287, A019288, A019289, A019290. %K A019291 nonn %O A019291 1,1 %A A019291 _N. J. A. Sloane_ %E A019291 More terms from _Jud McCranie_, Nov 13 2001 %E A019291 a(9) from _Jud McCranie_, Jan 28 2012 %E A019291 a(10) from _Giovanni Resta_, Feb 26 2020