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!)
A069082 Numbers n such that sigma(n)/tau(n) has denominator 3. 1
4, 9, 12, 25, 28, 52, 63, 75, 76, 84, 108, 117, 121, 124, 148, 156, 171, 172, 175, 180, 196, 228, 243, 244, 268, 279, 289, 292, 316, 325, 333, 363, 364, 372, 387, 388, 396, 412, 436, 441, 444, 475, 508, 516, 525, 529, 532, 549, 556, 588, 603, 604, 628, 652 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers such that the denominator of the fraction (sum of the divisors of n) divided by (the number of divisors of n) equals 3. - Harvey P. Dale, Jul 13 2012

LINKS

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

FORMULA

n such that A057021(n)=3.

MATHEMATICA

Select[Range[700], Denominator[DivisorSigma[1, #]/DivisorSigma[0, #]] == 3&] (* Harvey P. Dale, Jul 13 2012 *)

PROG

(MAGMA) [n:n in [1..700]|Denominator(SumOfDivisors(n)/#Divisors(n)) eq 3]; // Marius A. Burtea, Sep 08 2019

CROSSREFS

Cf. A000005, A000203, A057021.

Sequence in context: A199973 A320925 A212875 * A344415 A297414 A076794

Adjacent sequences:  A069079 A069080 A069081 * A069083 A069084 A069085

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre, Apr 05 2002

STATUS

approved

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 May 20 01:04 EDT 2022. Contains 353847 sequences. (Running on oeis4.)