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 A028499 #44 May 23 2025 06:59:26 %S A028499 301,16513,60110701,1977225901,2733834545701,232630479398401, %T A028499 336823287227717101 %N A028499 6-hyperperfect numbers: n = 6*(sigma(n) - n - 1) + 1. %C A028499 (7^k-6)*7^(k-1) is a term for all k in A191469. - _Max Alekseyev_, Nov 17 2019 %H A028499 Antal Bege, Kinga Fogarasi, <a href="http://www.acta.sapientia.ro/acta-math/C1-1/MATH1-6.PDF">Generalized perfect numbers</a>, Acta Univ. Sapientiae, Math., 1 (2009), 73-82. %H A028499 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. %H A028499 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HyperperfectNumber.html">Hyperperfect Number</a> %o A028499 (PARI) isok(n) = 6*(sigma(n) - n - 1) + 1 == n; \\ _Michel Marcus_, Nov 18 2019 %Y A028499 Cf. A000396, A007593, A028500, A028501, A028502, A034916, A220290. %K A028499 hard,more,nonn %O A028499 1,1 %A A028499 _Jud McCranie_ %E A028499 a(5) from _Donovan Johnson_, Nov 20 2012 %E A028499 a(6) from _Donovan Johnson_ confirmed by _Max Alekseyev_, Nov 17 2019 %E A028499 a(7) from _Giovanni Resta_ confirmed by _Max Alekseyev_, May 23 2025