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A147751
Number of nontrivial (i.e., containing two or more members) subsets of {1,2,3,...,n} whose geometric mean is an integer.
2
0, 0, 0, 2, 2, 2, 2, 4, 10, 10, 10, 16, 16, 16, 16, 24, 24, 52, 52, 54
OFFSET
1,4
EXAMPLE
For n=4, (1*4)^(1/2) = 2 and (1*2*4)^(1/3) = 2. No other subset of {1,2,3,4} has integer geometric mean, so a(4)=2.
CROSSREFS
Sequence in context: A162799 A034585 A171869 * A360315 A045948 A278110
KEYWORD
nonn
AUTHOR
John W. Layman, Nov 11 2008
STATUS
approved