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 A335269 #12 Jun 26 2020 09:14:12
%S A335269 228,345,1645,2120,4025,4386,4977,7725,8041,13026,23881,24157,24336,
%T A335269 51925,88473,115957,150161,169893,229177,255041,278721,322592,342637,
%U A335269 377201,490725,538625,656937,1497517,1566981,2132021,3256261,3847001,4646101,5054221,5524897
%N A335269 Numbers for which the harmonic mean of the nontrivial unitary divisors is an integer.
%C A335269 A number m is a term if the set {d|m ; d > 1, d < m, gcd(d, m/d) = 1} is nonempty and the harmonic mean its members is an integer.
%C A335269 The corresponding harmonic means are 8, 9, 15, 16, 25, 12, 21, 15, 33, 12, ...
%C A335269 Equivalently, numbers m such that omega(m) > 1 and (usigma(m)-m-1) | m*(2^omega(m)-2), where usigma is the sum of unitary divisors (A034448), and 2^omega(m)-2 = A034444(m)-2 = A087893 (m) is the number of the nontrivial unitary divisors of m.
%C A335269 The squarefree terms of A247078 are also terms of this sequence.
%H A335269 Amiram Eldar, <a href="/A335269/b335269.txt">Table of n, a(n) for n = 1..150</a>
%e A335269 228 is a term since the harmonic mean of its nontrivial unitary divisors, {3, 4, 12, 19, 57, 76} is 8 which is an integer.
%t A335269 usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); Select[Range[10^6], (omega = PrimeNu[#]) > 1 && Divisible[#*(2^omega - 2), usigma[#] - # - 1] &]
%Y A335269 The unitary version of A247078.
%Y A335269 Cf. A006086, A034444, A034448, A077610, A087893, A335268, A335270.
%K A335269 nonn
%O A335269 1,1
%A A335269 _Amiram Eldar_, May 29 2020