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A050347 Number of ways to factor n into distinct factors with 2 levels of parentheses. 3
1, 1, 1, 1, 1, 4, 1, 4, 1, 4, 1, 10, 1, 4, 4, 7, 1, 10, 1, 10, 4, 4, 1, 26, 1, 4, 4, 10, 1, 22, 1, 14, 4, 4, 4, 34, 1, 4, 4, 26, 1, 22, 1, 10, 10, 4, 1, 63, 1, 10, 4, 10, 1, 26, 4, 26, 4, 4, 1, 74, 1, 4, 10, 29, 4, 22, 1, 10, 4, 22, 1, 105, 1, 4, 10, 10, 4, 22, 1, 63, 7, 4, 1, 74, 4, 4, 4, 26 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,6
COMMENTS
a(n) depends only on prime signature of n (cf. A025487). So a(24) = a(375) since 24 = 2^3*3 and 375 = 3*5^3 both have prime signature (3,1).
LINKS
FORMULA
Dirichlet g.f.: Product_{n>=2}(1+1/n^s)^A050345(n).
a(n) = A050348(A101296(n)). - R. J. Mathar, May 26 2017
EXAMPLE
6 = ((6)) = ((3*2)) = ((3)*(2)) = ((3))*((2)).
CROSSREFS
Sequence in context: A174571 A099301 A244971 * A240226 A322515 A330571
KEYWORD
nonn
AUTHOR
Christian G. Bower, Oct 15 1999
STATUS
approved

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Last modified March 28 22:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)