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A050363 Number of ordered factorizations into prime powers greater than 1. +0
2
1, 1, 1, 2, 1, 2, 1, 4, 2, 2, 1, 5, 1, 2, 2, 8, 1, 5, 1, 5, 2, 2, 1, 12, 2, 2, 4, 5, 1, 6, 1, 16, 2, 2, 2, 14, 1, 2, 2, 12, 1, 6, 1, 5, 5, 2, 1, 28, 2, 5, 2, 5, 1, 12, 2, 12, 2, 2, 1, 18, 1, 2, 5, 32, 2, 6, 1, 5, 2, 6, 1, 37, 1, 2, 5, 5, 2, 6, 1, 28, 8, 2, 1, 18, 2, 2, 2, 12, 1, 18, 2, 5, 2, 2, 2, 64 (list; graph; listen)
OFFSET

1,4

COMMENT

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).

FORMULA

Dirichlet g.f.: 1/(1-B(s)) where B(s) is d.g.f. of characteristic function of prime powers >1.

CROSSREFS

Cf. A000961, A050360-A050364. a(p^k)=2^(n-1). a(A002110)=A000142=n!.

Sequence in context: A072342 A066389 A077191 this_sequence A166974 A111588 A070972

Adjacent sequences: A050360 A050361 A050362 this_sequence A050364 A050365 A050366

KEYWORD

nonn

AUTHOR

Christian G. Bower (bowerc(AT)usa.net), Oct 15 1999.

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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