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%I #15 Dec 24 2024 07:31:20
%S 1,0,1,1,1,1,0,1,1,1,0,2,0,1,0,0,1,2,0,2,0,0,0,3,0,1,0,1,0,3,0,2,1,0,
%T 0,2,0,1,0,1,0,2,0,1,0,0,0,3,0,2,0,0,0,3,0,1,0,0,0,4,0,1,0,0,1,0,0,2,
%U 0,1,0,6,0,1,0,0,0,1,0,3,0,1,0,3,0,0,0,0,0,4,0,0,0,0,0,4,0,1,0,1,0,2,0,2,0
%N Number of terms in inverse set of usigma = sum of unitary divisors = A034448.
%H Amiram Eldar, <a href="/A063974/b063974.txt">Table of n, a(n) for n = 1..10000</a>
%F Size of set {x; usigma(x) = n}.
%F Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = A308041. - _Amiram Eldar_, Dec 23 2024
%e usigma(x) = 288, invusigma(288) = {138,154,165,168,213,235,248,253}, so a(288) = 8, the number of all terms in the inverse set.
%Y Cf. A034444, A034448, A051444, A054973, A057637, A308041.
%K nonn,changed
%O 1,12
%A _Labos Elemer_, Sep 05 2001