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A178649 a(n) = product of nonsquarefree divisors of n. 2
1, 1, 1, 4, 1, 1, 1, 32, 9, 1, 1, 48, 1, 1, 1, 512, 1, 162, 1, 80, 1, 1, 1, 9216, 25, 1, 243, 112, 1, 1, 1, 16384, 1, 1, 1, 279936, 1, 1, 1, 25600, 1, 1, 1, 176, 405, 1, 1, 7077888, 49, 1250, 1, 208 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

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

FORMULA

a(n) = A007955(n) / A078599(n) = A007955(n) / A007955(A007947(n)).

a(1) = 1, a(p) = 1, a(pq) = 1, a(pq...z) = 1, a(p^k) = p^(1/2*k*(k+1)-1), for p, q = primes, k = natural numbers, pq...z = product of k (k > 2) distinct primes p, q, ..., z.

EXAMPLE

For n = 16, set of such divisors is {4, 8, 16}; a(16) = 4*8*16 = 512.

PROG

(Haskell)

a178649 n = div (a007955 n) (a078599 n)

-- Reinhard Zumkeller, Feb 06 2012

CROSSREFS

Sequence in context: A112622 A183104 A183102 * A119591 A304876 A010125

Adjacent sequences:  A178646 A178647 A178648 * A178650 A178651 A178652

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Dec 25 2010

STATUS

approved

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Last modified February 17 02:22 EST 2020. Contains 331976 sequences. (Running on oeis4.)