login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A216897 a(n) = smallest m such that sigma(m)/m = n + 1/3. 0
3, 12, 1080, 18506880, 2198278051200, 28657168334177779210174055055360000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

An upper bound for a(7) is a 77-digit number with factorization: 2^35 3^20 5^9 7^3 11 13^2 17 19 23 29 31 37^2 41 61 67 71 73 109 137 409 521 547 1093 36809 368089.

An upper bound for a(8) is a 165-digit number that can be found on given link where line begins with 25/3.

LINKS

Table of n, a(n) for n=1..6.

Walter Nissen and Michel Marcus, Extended Table of Abundancies

EXAMPLE

a(1) = 3 because sigma(3)/3 = 4/3 = 1 + 1/3 and 3 is the earliest m such that sigma(m)/m = 1 + 1/3.

CROSSREFS

Cf. A160320, A088912.

Sequence in context: A132515 A279122 A246957 * A262541 A036300 A169815

Adjacent sequences:  A216894 A216895 A216896 * A216898 A216899 A216900

KEYWORD

nonn

AUTHOR

Michel Marcus, Sep 19 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 21 19:59 EDT 2021. Contains 345365 sequences. (Running on oeis4.)