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 A341623 #25 Oct 02 2021 04:17:07
%S A341623 28,90,496,546,8128,33550336,8589869056,137438691328,
%T A341623 2305843008139952128,2658455991569831744654692615953842176
%N A341623 Numbers k such that sigma(3*k) = 8*k.
%C A341623 Every perfect number P greater than 6 (so, P is not divisible by 3) will be found in this sequence. Proof: sigma(3*P) = sigma(3)*sigma(P) = 4*(2*P) = 8*P. - _Timothy L. Tiffin_, Aug 26 2021
%C A341623 Solutions are integers y/3 where sigma(y)/y = 8/3. - _Michel Marcus_, Aug 27 2021
%e A341623 546 is a term, since sigma(3*546) = sigma(1638) = 4368 = 8*546. - _Timothy L. Tiffin_, Aug 26 2021
%t A341623 Select[Range[5*10^9], DivisorSigma[1, 3*#] == 8*# &] (* _Timothy L. Tiffin_, Aug 26 2021 *)
%t A341623 Do[If[DivisorSigma[1, 3*k] == 8*k, Print[k]], {k, 5*10^9}] (* _Timothy L. Tiffin_, Aug 26 2021 *)
%Y A341623 Cf. A000396 (subsequence, apart from its terms that are divisible by 3).
%Y A341623 Subsequence of A005101 and A227303.
%Y A341623 Cf. also A000203, A144613, A326051, A336702, A347261.
%K A341623 nonn,more
%O A341623 1,1
%A A341623 _Antti Karttunen_, Feb 19 2021
%E A341623 a(7)-a(8) from _Martin Ehrenstein_, Mar 06 2021
%E A341623 a(9)-a(10) from _Michel Marcus_, Aug 27 2021