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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

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Last modified October 31 00:58 EDT 2014. Contains 248845 sequences.