Is the sequence defined by -LSB- math -RSB- s_n = \ left -LRB- \ frac -LCB- -1 -RCB- -LCB- 5 -RCB- \ right -RRB- ^ n -LSB- / math -RSB- a cauchy sequence ?
A sequence is defined recursively using the formula f -LRB- n + 1 -RRB- = -- 0.5 f -LRB- n -RRB- . If the first term of the sequence is 120 , what is f -LRB- 5 -RRB- ?