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

 

Logo

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A056624 Number of unitary square divisors of n. 2
1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 2, 4, 1, 1, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Unitary analogue of A046951.

LINKS

Table of n, a(n) for n=1..105.

FORMULA

a(n)=2^r, where r is the number of prime factors of the largest unitary square divisor of n.

Multiplicative with a(p^e) = 2^(1-(e mod 2)). - Vladeta Jovovic, Dec 13 2002

EXAMPLE

n=256, it has 5 square divisors of which only 2,{1,256} are unitary,3 divisors are not; n=124 has 2 (1 and 4) square divisors, both of them unitary a(124)=2. n=108 has 12 divisors,4 square divisors: {1,4,9,36} of which 1 and 4 are unitary, 9 and 36 are not.So a(108)=2. The largest ubutary square divisor of 108 is 4 with 1 prime divisor so a(108)=2^1=2.

CROSSREFS

A046952, A034444, A000188, A008833, A055229.

Sequence in context: A133912 A122934 A072170 * A193348 A093997 A157196

Adjacent sequences:  A056621 A056622 A056623 * A056625 A056626 A056627

KEYWORD

nonn,mult

AUTHOR

Labos Elemer, Aug 08 2000

EXTENSIONS

More terms from Vladeta Jovovic, Dec 13 2002

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified November 26 14:56 EST 2014. Contains 250079 sequences.