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 A205643 #25 Jun 02 2025 07:39:37 %S A205643 2,84,480,32256,58254,61440,1556480,3932160,1505806848,107870873600, %T A205643 1098437885952 %N A205643 (2,k)-perfect numbers (A019278) such that the next (2,k)-perfect number has the same value of k (in A098223). %C A205643 a(12) > 4*10^12, if it exists. - _Giovanni Resta_, Feb 26 2020 %Y A205643 Cf. A019278, A098223. %K A205643 nonn,more %O A205643 1,1 %A A205643 _Jud McCranie_, Feb 08 2012 %E A205643 a(11) from _Giovanni Resta_, Feb 26 2020