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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.
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%I #8 Feb 10 2022 18:59:11

%S 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 39,41,42,43,46,47,51,53,55,57,58,59,61,62,65,66,67,69,70,71,73,74,77,

%U 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 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 Conjectured to be the union of A005117 and A063880.

%H Antti Karttunen, <a href="/A348506/b348506.txt">Table of n, a(n) for n = 1..20000</a>

%o (PARI)

%o A034448(n) = { my(f=factorint(n)); prod(k=1, #f~, 1+(f[k, 1]^f[k, 2])); }; \\ After code in A034448

%o isA348506(n) = !(sigma(n)%A034448(n));

%Y Positions of ones in A348505.

%Y Cf. A005117 and A063880.

%Y Cf. A000203, A034448.

%K nonn

%O 1,2

%A _Antti Karttunen_, Oct 29 2021