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.

A329731 Numbers k such that the sum of distinct prime divisors of k divides the sum of unitary divisors of k.

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%I A329731 #8 Nov 21 2019 04:20:40
%S A329731 12,15,18,35,36,42,56,60,63,66,72,75,90,95,108,110,114,119,126,132,
%T A329731 135,143,144,147,153,168,180,192,195,209,220,245,250,258,260,264,287,
%U A329731 288,290,294,297,300,308,312,315,319,322,323,324,338,342,360,375,377,378
%N A329731 Numbers k such that the sum of distinct prime divisors of k divides the sum of unitary divisors of k.
%C A329731 The unitary version of A070222.
%H A329731 Amiram Eldar, <a href="/A329731/b329731.txt">Table of n, a(n) for n = 1..10000</a>
%e A329731 12 is in the sequence since its sum of unitary divisors, 1 + 3 + 4 + 12 = 20, is divisible by its sum of distinct prime divisors, 2 + 3 = 5.
%t A329731 aQ[n_] := Divisible[Times @@ (1 + Power @@@ (f = FactorInteger[n])), Total[First /@ f]]; Select[Range[2, 400], aQ]
%Y A329731 Cf. A008472, A034448, A070222.
%K A329731 nonn
%O A329731 1,1
%A A329731 _Amiram Eldar_, Nov 19 2019