Insert 4 real G.Ms between 3 and 96.

Sequence: (3,\ G_1,G_2,G_3,G_4,\ 96) (6 terms)

[ 96=3\cdot r^5\implies r^5=32\implies r=2 ]

G.Ms: (6,\ 12,\ 24,\ 48)

Answer: (6,12,24,48)