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A064374 Numbers k such that sigma(k) > phi(k)^2. 2
2, 4, 6, 10, 12, 18, 30 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also numbers k such that sigma(k) > tau(k)*phi(k). - Benoit Cloitre, Aug 06 2002

There are no further terms. - Benoit Cloitre, Aug 06 2002

LINKS

Table of n, a(n) for n=1..7.

FORMULA

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

EXAMPLE

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

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

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

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

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

No more solutions below 10000000.

CROSSREFS

Cf. A000010, A000203, A055234.

Sequence in context: A324059 A055235 A083887 * A000885 A068336 A293821

Adjacent sequences:  A064371 A064372 A064373 * A064375 A064376 A064377

KEYWORD

nonn,fini,full

AUTHOR

Labos Elemer, Sep 27 2001

STATUS

approved

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Last modified August 25 09:44 EDT 2019. Contains 326324 sequences. (Running on oeis4.)