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A348506 Numbers k such that sigma(k) is a multiple of usigma(k), where sigma is the sum of divisors function, A000203, and usigma is the unitary sigma, A034448.

%I A348506 #8 Feb 10 2022 18:59:11
%S A348506 1,2,3,5,6,7,10,11,13,14,15,17,19,21,22,23,26,29,30,31,33,34,35,37,38,
%T A348506 39,41,42,43,46,47,51,53,55,57,58,59,61,62,65,66,67,69,70,71,73,74,77,
%U A348506 78,79,82,83,85,86,87,89,91,93,94,95,97,101,102,103,105,106,107,108,109,110,111,113,114,115,118,119
%N A348506 Numbers k such that sigma(k) is a multiple of usigma(k), where sigma is the sum of divisors function, A000203, and usigma is the unitary sigma, A034448.
%C A348506 Conjectured to be the union of A005117 and A063880.
%H A348506 Antti Karttunen, <a href="/A348506/b348506.txt">Table of n, a(n) for n = 1..20000</a>
%o A348506 (PARI)
%o A348506 A034448(n) = { my(f=factorint(n)); prod(k=1, #f~, 1+(f[k, 1]^f[k, 2])); }; \\ After code in A034448
%o A348506 isA348506(n) = !(sigma(n)%A034448(n));
%Y A348506 Positions of ones in A348505.
%Y A348506 Cf. A005117 and A063880.
%Y A348506 Cf. A000203, A034448.
%K A348506 nonn
%O A348506 1,2
%A A348506 _Antti Karttunen_, Oct 29 2021