

A227243


Powerful numbers n such that n/phi(n) >= e^gamma*log log n.


1



4, 8, 9, 16, 36, 72, 108, 144, 216, 900, 1800, 2700, 3600, 44100, 88200
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OFFSET

1,1


COMMENTS

The sequence is complete.


LINKS

Table of n, a(n) for n=1..15.
Eric Weisstein's World of Mathematics, Totient Function
Index entries for sequences related to powerful numbers


FORMULA

A001694 INTERSECT A100966.


MATHEMATICA

PowerfulQ[1] := True; PowerfulQ[n_Integer?Positive] := Min[Last /@ FactorInteger[n]] > 1; Select[Range[100], PowerfulQ[#] && #/EulerPhi[#] >= E^EulerGamma*Log[Log[#]] &] (* G. C. Greubel, Oct 02 2017 *)


PROG

(PARI) a=exp(Euler); for(n=4, 88200, if(ispowerful(n)&&n/eulerphi(n)>=a*log(log(n)), print1(n, ", ")));


CROSSREFS

Cf. A001694, A100966.
Sequence in context: A227645 A285438 A089042 * A272575 A020145 A202271
Adjacent sequences: A227240 A227241 A227242 * A227244 A227245 A227246


KEYWORD

nonn,easy,fini,full


AUTHOR

Arkadiusz Wesolowski, Oct 20 2013


STATUS

approved



