cp's OEIS Frontend

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.

A357605 Numbers k such that A162296(k) > 2*k.

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%I A357605 #12 Oct 26 2022 07:59:31
%S A357605 36,48,72,80,96,108,120,144,160,162,168,180,192,200,216,224,240,252,
%T A357605 264,270,280,288,300,312,320,324,336,352,360,378,384,392,396,400,408,
%U A357605 416,432,448,450,456,468,480,486,500,504,528,540,552,560,576,588,594,600,612
%N A357605 Numbers k such that A162296(k) > 2*k.
%C A357605 The least odd term is a(470) = A357607(1) = 4725.
%C A357605 The numbers of terms not exceeding 10^k, for k = 2, 3, ..., are 5, 92, 1011, 10160, 102125, 1022881, 10231151, 102249758, 1022781199, 10229781638, ... . Apparently, the asymptotic density of this sequence exists and equals 0.102... .
%C A357605 An analog of abundant numbers, in which the divisor sum is restricted to nonsquarefree divisors. - _Peter Munn_, Oct 26 2022
%H A357605 Amiram Eldar, <a href="/A357605/b357605.txt">Table of n, a(n) for n = 1..10000</a>
%e A357605 36 is a term since A162296(36) = 79 > 2*36.
%t A357605 q[n_] := Module[{f = FactorInteger[n], p, e}, p = f[[;; , 1]]; e = f[[;; , 2]]; Times @@ ((p^(e + 1) - 1)/(p - 1)) - Times @@ (p + 1) > 2*n]; Select[Range[2, 1000], q]
%Y A357605 Cf. A162296.
%Y A357605 Subsequence of A005101 and A013929.
%Y A357605 Similar sequences: A034683, A064597, A129575, A129656, A292982, A348274, A348604.
%K A357605 nonn
%O A357605 1,1
%A A357605 _Amiram Eldar_, Oct 06 2022