1,4

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)=3.

A147751, A147753

Sequence in context: A111233 A105159 A050499 this_sequence A114227 A112593 A113215

Adjacent sequences: A147749 A147750 A147751 this_sequence A147753 A147754 A147755

nonn

John W. Layman (layman(AT)math.vt.edu), Nov 11 2008