A176598 - OEIS

A176598

Numbers n such that phi(n)/n = 16/41.

410, 820, 1640, 2050, 3280, 4100, 6560, 8200, 10250, 13120, 16400, 16810, 20500, 26240, 32800, 33620, 41000, 51250, 52480, 65600, 67240, 82000, 84050, 102500, 104960, 131200, 134480, 164000, 168100, 205000, 209920, 256250, 262400, 268960, 328000, 336200

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OFFSET

1,1

COMMENTS

Phi(.)= A000010(.) is the Euler totient function.

REFERENCES

J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 410, p. 91, Ellipses, Paris 2008.

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..500

H. Fripertinger, The Euler phi function

Wikipedia, Euler's totient function

FORMULA

41n < a(n) <= 205 * 2^n. - Charles R Greathouse IV, May 15 2013

EXAMPLE

For n = 410, phi(410)/410 = 160/410 = 16/41, which puts 410 into the sequence.

MAPLE

with(numtheory): ii:=1: N0:=40: tabl:=array(1..N0+1): for n from 1 to 540000 do : if 41*phi(n)=16*n then tabl[ii]:= n: ii:= ii+1: fi: od: print(tabl):

PROG

(PARI) is(n)=eulerphi(n)/n==16/41 \\ Charles R Greathouse IV, May 15 2013

CROSSREFS

Cf. A172344.

Sequence in context: A238753 A157431 A179129 * A146075 A374270 A212710

Adjacent sequences: A176595 A176596 A176597 * A176599 A176600 A176601

KEYWORD

nonn

AUTHOR

Michel Lagneau, Apr 21 2010

EXTENSIONS

Link to b-file of another sequence removed - R. J. Mathar, Oct 20 2010

STATUS

approved