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 A348923 #13 Nov 07 2021 02:13:10 %S A348923 45,60,3780,64260,3112200,6320160 %N A348923 Numbers that are both unitary and nonunitary harmonic numbers. %C A348923 a(7) > 10^12, if it exists. %C A348923 For each term the two sets of unitary and nonunitary divisors both contain more than one element. The only number with a single unitary divisor is 1 which does not have nonunitary divisors. Numbers with a single nonunitary divisor are the squares of primes which are not unitary harmonic numbers. Therefore, this sequence is a subsequence of A348715. %C A348923 Nonsquarefree numbers k such that A034448(k) divides k*A034444(k) and A048146(k) divides k*A048105(k). - _Daniel Suteu_, Nov 05 2021 %e A348923 45 is a term since the unitary divisors of 45 are 1, 5, 9 and 45, and their harmonic mean is 3, and the nonunitary divisors of 45 are 3 and 15, and their harmonic mean is 5. %t A348923 usigma[1] = 1; usigma[n_] := Times @@ (1 + Power @@@ FactorInteger[n]); Select[Range[65000], !SquareFreeQ[#] && IntegerQ[# * (d = 2^PrimeNu[#])/ (s = usigma[#])] && IntegerQ[# * (DivisorSigma[0, #] - d)/(DivisorSigma[1, #] - s)] &] %Y A348923 Intersection of A006086 and A319745. %Y A348923 Subsequence of A348715. %Y A348923 Cf. A348922. %Y A348923 Cf. A034444, A034448, A048105, A048146. %K A348923 nonn,more %O A348923 1,1 %A A348923 _Amiram Eldar_, Nov 04 2021