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 A064374 Numbers k such that sigma(k) > phi(k)^2. 2

%I

%S 2,4,6,10,12,18,30

%N Numbers k such that sigma(k) > phi(k)^2.

%C Also numbers k such that sigma(k) > tau(k)*phi(k). - _Benoit Cloitre_, Aug 06 2002

%C There are no further terms. - _Benoit Cloitre_, Aug 06 2002

%F Solutions to A000203(k) > A000010(k)^2.

%e k = {2, 4, 6, 10, 12, 18, 30};

%e sigma(k) = {3, 7, 12, 18, 28, 39, 72};

%e phi(k) = {1, 2, 2, 4, 4, 6, 8};

%e phi(k)^2 = {1, 4, 4, 16, 16, 36, 64};

%e sigma(k) - phi(k)^2 = {2, 3, 8, 2, 12, 3, 8}.

%e No more solutions below 10000000.

%Y Cf. A000010, A000203, A055234.

%K nonn,fini,full

%O 1,1

%A _Labos Elemer_, Sep 27 2001

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Last modified August 9 01:18 EDT 2020. Contains 336310 sequences. (Running on oeis4.)