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 A033855 #21 Oct 10 2023 05:17:15 %S A033855 1,2,7,9,29,143,155,183,731,791,1011,1346,35659,60484,65524,525227, %T A033855 525557,525617,526697,529817,531779,567437,1047554,2541679,33550337, %U A033855 214486281,1476844097,1478227937,1543409687,14200144243,14200244477,14200257551,14200349281,14200779611,14201040053,14201501401 %N A033855 Numbers k such that j(k)*phi(k) = s(phi(k)), where j(k) = A033831(k), s(k) = sigma(k) - k. %C A033855 phi(a(n)) is a multiperfect number (A007691). - _Max Alekseyev_, Oct 09 2023 %H A033855 Max Alekseyev, <a href="/A033855/b033855.txt">Table of n, a(n) for n = 1..50000</a> %t A033855 j[n_] := DivisorSum[n, 1&, # > 2 && n/# < #-1 &]; aQ[n_] := j[n] * (p = EulerPhi[ n]) == DivisorSigma[1, p] - p; Select[Range[10^4], aQ] (* _Amiram Eldar_, Jul 01 2019 *) %Y A033855 Cf. A000010, A000203, A001065, A007691, A033831, A033856. %K A033855 nonn %O A033855 1,2 %A A033855 _Naohiro Nomoto_ %E A033855 More terms from _Amiram Eldar_, Jul 01 2019 %E A033855 Terms a(27) onward from _Max Alekseyev_, Oct 09 2023