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A050349 Number of ways to factor n into distinct factors with 3 levels of parentheses. 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; 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)^A050347(n).
a(n) = A050350(A101296(n)). - R. J. Mathar, May 26 2017
EXAMPLE
6 = (((6))) = (((3*2))) = (((3)*(2))) = (((3))*((2))) = (((3)))*(((2))).
CROSSREFS
Sequence in context: A176260 A098190 A339353 * A083528 A056957 A224834
KEYWORD
nonn
AUTHOR
Christian G. Bower, Oct 15 1999
STATUS
approved

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Last modified March 18 22:56 EDT 2024. Contains 370952 sequences. (Running on oeis4.)