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

 

Logo

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A138224 a(n) = the nearest divisor of n to the number of positive divisors of n. In case of tie, round down. 4
1, 2, 1, 2, 1, 3, 1, 4, 3, 5, 1, 6, 1, 2, 3, 4, 1, 6, 1, 5, 3, 2, 1, 8, 1, 2, 3, 7, 1, 6, 1, 4, 3, 2, 5, 9, 1, 2, 3, 8, 1, 7, 1, 4, 5, 2, 1, 8, 1, 5, 3, 4, 1, 9, 5, 8, 3, 2, 1, 12, 1, 2, 7, 8, 5, 6, 1, 4, 3, 7, 1, 12, 1, 2, 5, 4, 1, 6, 1, 10, 3, 2, 1, 12, 5, 2, 3, 8, 1, 10, 1, 4, 3, 2, 5, 12, 1, 7, 3, 10, 1, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..102.

EXAMPLE

There are four positive divisors of 15: (1,3,5,15). There are two divisors, 3 and 5, that are nearest 4. We take the smaller divisor, 3 in this case, in case of a tie; so a(15) = 3.

MAPLE

A138224 := proc(n) if n = 1 then RETURN(1); fi; t := numtheory[tau](n) ; dvs := sort(convert(numtheory[divisors](n), list)) ; a := op(1, dvs) ; for i from 2 to nops(dvs) do if abs(op(i, dvs) - t) < abs(a-t) then a := op(i, dvs) ; fi; od: a ; end: seq(A138224(n), n=1..120) ; # R. J. Mathar, Jul 20 2009

CROSSREFS

Cf. A138221, A138222, A138223, A000005.

Sequence in context: A029216 A153174 A138222 * A181472 A271825 A271875

Adjacent sequences:  A138221 A138222 A138223 * A138225 A138226 A138227

KEYWORD

nonn

AUTHOR

Leroy Quet, Mar 06 2008

EXTENSIONS

Extended beyond a(15) by R. J. Mathar, Jul 20 2009

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified December 9 14:26 EST 2016. Contains 278971 sequences.