login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A136528 a(n) = the highest possible number of positive divisors of the sum of any two distinct positive divisors of n. 1
2, 3, 4, 4, 4, 4, 6, 6, 6, 6, 6, 4, 5, 6, 8, 6, 8, 6, 8, 8, 8, 8, 9, 8, 6, 9, 8, 8, 9, 6, 10, 9, 9, 9, 10, 4, 8, 8, 12, 8, 10, 6, 10, 12, 10, 10, 12, 8, 12, 8, 8, 8, 12, 12, 12, 12, 12, 12, 12, 4, 7, 12, 12, 8, 12, 6, 12, 12, 12, 12, 12, 4, 6, 12, 10, 12, 12, 10, 16, 12, 12, 12, 12, 12, 8, 12, 12, 12, 16, 8, 12, 12, 12, 12, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

There are d(n)*(d(n)-1)/2 sums of pairs of distinct positive divisors of n, where d(n) = number of positive divisors of n.

LINKS

Table of n, a(n) for n=2..96.

EXAMPLE

The positive divisors of 6 are 1,2,3,6. Letting d(m) = the number of positive divisors of m: d(1+2)=2; d(1+3)=3; d(1+6)=2; d(2+3)=2; d(2+6)=4; d(3+6)=3. The maximum of these values is 4, so a(6) = 4.

CROSSREFS

Cf. A136529.

Sequence in context: A064004 A195849 A087827 * A263252 A276334 A225486

Adjacent sequences:  A136525 A136526 A136527 * A136529 A136530 A136531

KEYWORD

nonn

AUTHOR

Leroy Quet, Jan 03 2008

EXTENSIONS

More terms from Sean A. Irvine, Feb 28 2011

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 May 24 14:49 EDT 2019. Contains 323532 sequences. (Running on oeis4.)