id:A050349 - OEIS Search Results

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Number of ways to factor n into distinct factors with 3 levels of parentheses.

+0
2

1, 1, 1, 1, 1, 5, 1, 5, 1, 5, 1, 15, 1, 5, 5, 11, 1, 15, 1, 15, 5, 5, 1, 45, 1, 5, 5, 15, 1, 35, 1, 25, 5, 5, 5, 65, 1, 5, 5, 45, 1, 35, 1, 15, 15, 5, 1, 130, 1, 15, 5, 15, 1, 45, 5, 45, 5, 5, 1, 145, 1, 5, 15, 60, 5, 35, 1, 15, 5, 35, 1, 240, 1, 5, 15, 15, 5, 35, 1, 130, 11, 5, 1, 145, 5 (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=2 to inf}(1+1/n^s)^A050347(n).`
	EXAMPLE	`6=(((6)))=(((32)))=(((3)(2)))=(((3))((2)))=(((3)))(((2))).`
	CROSSREFS	`Cf. A045778, A050345-A050350. a(p^k)=A050344. a(A002110)=A000357.` `Sequence in context: A010686 A021070 A098190 this_sequence A083528 A056957 A095118` `Adjacent sequences: A050346 A050347 A050348 this_sequence A050350 A050351 A050352`
	KEYWORD	`nonn`
	AUTHOR	`Christian G. Bower (bowerc(AT)usa.net), Oct 15 1999.`

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Last modified December 10 12:37 EST 2009. Contains 170569 sequences.

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