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 A348922 #13 Nov 07 2021 02:12:56
%S A348922 45,60,54600,257040,1801800,2789640,4299750,47297250,1707259680,
%T A348922 4093362000
%N A348922 Numbers that are both infinitary and noninfinitary harmonic numbers.
%C A348922 a(11) > 10^10.
%C A348922 For each term the two sets of infinitary and noninfinitary divisors both contain more than one element. The only number with a single infinitary divisor is 1 which does not have noninfinitary divisors. Numbers with a single noninfinitary divisor are the squares of primes which are not infinitary harmonic numbers. Therefore, this sequence is a subsequence of A348715.
%C A348922 Nonsquarefree numbers k such that A049417(k) divides k*A037445(k) and A348271(k) divides k*A348341(k). The sequence also includes: 18779856480, 44425017000, 13594055202000, 27188110404000, 299069214444000, 6824215711404000. - _Daniel Suteu_, Nov 06 2021
%e A348922 45 is a term since the infinitary divisors of 45 are 1, 5, 9 and 45, and their harmonic mean is 3, and the noninfinitary divisors of 45 are 3 and 15, and their harmonic mean is 5.
%t A348922 f[p_, e_] := Module[{b = IntegerDigits[e, 2], m}, m = Length[b]; Product[If[b[[j]] > 0, 1 + p^(2^(m - j)), 1], {j, 1, m}]]; isigma[1] = 1; isigma[n_] := Times @@ f @@@ FactorInteger[n]; id[1] = 1; id[n_] := Times @@ Flatten[2^DigitCount[#, 2, 1]& /@ FactorInteger[n][[;; , 2]] ]; pow2Q[n_] := n == 2^IntegerExponent[n, 2]; Select[Range[3*10^5], !pow2Q[DivisorSigma[0, #]] && IntegerQ[# * (d = id[#])/(s = isigma[#])] && IntegerQ[# * (DivisorSigma[0, #] - d)/(DivisorSigma[1, #] - s)] &]
%Y A348922 Intersection of A063947 and A348918.
%Y A348922 Subsequence of A348715.
%Y A348922 Cf. A348923.
%Y A348922 Cf. A037445, A049417, A348271, A348341.
%K A348922 nonn,more
%O A348922 1,1
%A A348922 _Amiram Eldar_, Nov 04 2021