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 A028501 #27 Nov 21 2019 15:00:46 %S A028501 1333,1909,2469601,893748277,322685352001,8992165119733, %T A028501 42052982615431201 %N A028501 18-hyperperfect numbers: n = 18*(sigma(n)-n-1) + 1. %C A028501 1978419655654505210563957 are also terms. - _Donovan Johnson_, Nov 20 2012 %C A028501 a(8) > 10^17. - _Max Alekseyev_, Nov 17 2019 %H A028501 Judson S. McCranie, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL3/mccranie.html">A Study of Hyperperfect Numbers</a>, Journal of Integer Sequences, Vol. 3 (2000), Article 00.1.3. %Y A028501 Cf. A000396, A007593, A220290, A028499, A028500, A028502, A034916. %K A028501 hard,more,nonn %O A028501 1,1 %A A028501 _Jud McCranie_ %E A028501 a(5) from _Donovan Johnson_, Nov 03 2011 %E A028501 a(6)-a(7) from _Donovan Johnson_ confirmed by _Max Alekseyev_, Nov 21 2019