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 A333873 #11 Apr 09 2020 05:24:03 %S A333873 3,5,17,257,413,611,1391,1589,1903,2327,5599,27959,29623,36647,36983, %T A333873 38863,42851,43919,46463,49513,65537,76759,82969,86567,88759,96839, %U A333873 111179,116479,129307,171191,184979,213041,277619,301157,310519,346151,362263,372227,375167 %N A333873 Numbers that equal to the sum of their iterated absolute Möbius divisor function (A173557). %C A333873 A variant of A082897 (perfect totient numbers) in which the absolute Möbius divisor function (A173557) replaces the Euler totient function (A000010). %H A333873 Amiram Eldar, <a href="/A333873/b333873.txt">Table of n, a(n) for n = 1..350</a> (terms below 4*10^9) %H A333873 Daeyeoul Kim, Umit Sarp, and Sebahattin Ikikardes, <a href="https://doi.org/10.3390/math7111083">Iterating the Sum of Möbius Divisor Function and Euler Totient Function</a>, Mathematics, Vol. 7, No. 11 (2019), pp. 1083-1094. %e A333873 5 is a term since A173557(5) = 4, A173557(4) = 1, and 4 + 1 = 5. %t A333873 f[p_, e_] := p - 1; u[1] = 1; u[n_] := Times @@ (f @@@ FactorInteger[n]); Select[Range[10^4], Plus @@ FixedPointList[u, #] == 2*# + 1 &] %Y A333873 A019434 is a subsequence. %Y A333873 Cf. A082897, A173557, A286067, A330273, A333871. %K A333873 nonn %O A333873 1,1 %A A333873 _Amiram Eldar_, Apr 08 2020