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A072048 Number of divisors of the squarefree numbers: tau(A005117(n)). 4
1, 2, 2, 2, 4, 2, 4, 2, 2, 4, 4, 2, 2, 4, 4, 2, 4, 2, 8, 2, 4, 4, 4, 2, 4, 4, 2, 8, 2, 4, 2, 4, 2, 4, 4, 4, 2, 2, 4, 4, 8, 2, 4, 8, 2, 2, 4, 4, 8, 2, 4, 2, 4, 4, 4, 2, 4, 4, 4, 4, 2, 2, 8, 2, 8, 4, 2, 2, 8, 4, 2, 8, 4, 4, 4, 4, 4, 2, 4, 8, 2, 4, 4, 2, 8, 2, 4, 4, 4, 4, 4, 2, 2, 8, 4, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) = 2^A072047(n) = 2^A001221(A005117(n)).

Also the number of cubefree numbers with the same squarefree kernel as the n-th squarefree number, see A073245.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A000005(A005117(n)).

MAPLE

A072048:=n->`if`(numtheory[issqrfree](n) = true, numtheory[tau](n), NULL); seq(A072048(k), k=1..100); # Wesley Ivan Hurt, Oct 13 2013

PROG

(Haskell)

a072048 = (2 ^) . a072047  -- Reinhard Zumkeller, Dec 13 2015

CROSSREFS

Cf. A062822.

Cf. A000079, A001221, A005117, A072047.

Sequence in context: A079405 A332347 A201353 * A161841 A335901 A152674

Adjacent sequences:  A072045 A072046 A072047 * A072049 A072050 A072051

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Jun 09 2002

STATUS

approved

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Last modified May 16 14:39 EDT 2021. Contains 343949 sequences. (Running on oeis4.)