login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A064374 Numbers k such that sigma(k) > phi(k)^2. 2

%I #12 Sep 04 2017 23:23:09

%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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 05:48 EDT 2024. Contains 371265 sequences. (Running on oeis4.)