id:A050320 - OEIS Search Results

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Number of ways n is a product of square-free numbers > 1.

+0
4

1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 2, 1, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 5, 1, 1, 2, 2, 2, 3, 1, 2, 2, 2, 1, 5, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 2, 1, 6, 1, 2, 2, 1, 2, 5, 1, 2, 2, 5, 1, 3, 1, 2, 2, 2, 2, 5, 1, 2, 1, 2, 1, 6, 2, 2, 2, 2, 1, 6, 2, 2, 2, 2, 2, 2, 1, 2, 2, 3, 1, 5, 1 (list; graph; listen)

	OFFSET	`1,6`
	COMMENT	`a(n) depends only on prime signature of n (cf. A025487). So a(24) = a(375) since 24=2^33 and 375=35^3 both have prime signature (3,1).`
	FORMULA	`Dirichlet g.f.: prod{n is square-free and > 1}(1/(1-1/n^s)).`
	CROSSREFS	`Cf. A001055, A005117, A050325. a(p^k)=1. a(A002110)=A000110.` `a(n!)=A103774(n).` `Sequence in context: A064372 A096825 A007875 this_sequence A121382 A051265 A008647` `Adjacent sequences: A050317 A050318 A050319 this_sequence A050321 A050322 A050323`
	KEYWORD	`nonn,easy,nice`
	AUTHOR	`Christian G. Bower (bowerc(AT)usa.net), Sep 15 1999.`

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Last modified December 4 23:11 EST 2009. Contains 170347 sequences.

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