A069167 - OEIS

A069167

Numbers k such that k*Sum_{d|k} 1/phi(d) is an integer.

1, 2, 4, 6, 8, 9, 10, 12, 16, 18, 24, 32, 36, 42, 44, 48, 50, 54, 64, 72, 81, 90, 96, 100, 108, 114, 126, 128, 144, 150, 162, 184, 192, 198, 200, 216, 234, 250, 252, 256, 288, 294, 324, 378, 384, 396, 400, 432, 441, 450, 484, 486, 504, 512, 550, 558, 576, 588

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OFFSET

1,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

MATHEMATICA

Select[Range[600], IntegerQ[#(Total[1/(EulerPhi[Divisors[#]])])]&](* Harvey P. Dale, Dec 17 2018 *)

PROG

(PARI) is(n)=denominator(sumdiv(n, d, 1/eulerphi(d))*n)==1 \\ Charles R Greathouse IV, Oct 27 2015

CROSSREFS

Cf. A000010.

Sequence in context: A070089 A371169 A353759 * A331226 A359825 A347450

Adjacent sequences: A069164 A069165 A069166 * A069168 A069169 A069170

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Apr 09 2002

STATUS

approved