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 A335830 #11 Jan 26 2021 05:59:22
%S A335830 1,2,1,4,4,0,7,6,0,8,5,9,1,4,2,7,1,9,2,9,0,6,3,8,6,3,7,3,9,0,8,2,1,8,
%T A335830 5,6,7,8,2,2,2,7,0,6,3,1,2,8,3,4,0,8,9,0,1,1,8,6,5,6,3,9,6,2,4,2,3,9,
%U A335830 9,3,3,9,0,1,7,8,4,4,8,4,1,6,8,0,7,8,8,8,0,0,0,8,8,8,8,6,1,9,2,9
%N A335830 Decimal expansion of the sum of the reciprocals of the multiply-perfect numbers.
%C A335830 The first 18 terms were calculated by Bayless and Kinlaw (2015).
%H A335830 Jonathan Bayless and Paul Kinlaw, <a href="https://www.researchgate.net/publication/288826545_On_repeated_values_of_s_and_multiperfect_numbers">On repeated values of sigma and multiperfect numbers</a>, Journal of Combinatorics and Number Theory, Vol. 7, No. 3 (2015), pp. 177-189.
%F A335830 Equals Sum_{k>=1} 1/A007691(k).
%e A335830 1.21440760859142719...
%t A335830 multiPerfects = Cases[Import["https://oeis.org/A007691/b007691.txt", "Table"], {_, _}][[;; , 2]]; RealDigits[Total[1/multiPerfects], 10, 18][[1]]
%Y A335830 Cf. A007691, A335118.
%K A335830 nonn,cons
%O A335830 1,2
%A A335830 _Amiram Eldar_, Jun 25 2020
%E A335830 More terms (computed using the b-file at A007691) from _Jon E. Schoenfield_, Jan 25 2021