The rule for this is (3n)/2.
16 x 3 = 48, 48/2 = 24.
24 x 3 = 72, 72/2 = 36.
36 x 3 = 108, 108/2 = 54.
54 x 3 = 162, 162/2 = 81.
81 x 3 = 243, 243/2 = 121.5.
121.5 x 3 = 364.5, 364.5/2 = 182.25.
182.25 x 3 = 546.75, 546.75/2 = 273.375
The 7th term is 273.375.
I hope this helps!