How does one calculate -LSB- math -RSB- \ frac -LCB- 1 -RCB- -LCB- 1 \ times 2 -RCB- -LSB- / math -RSB- + -LSB- math -RSB- \ frac -LCB- 1 -RCB- -LCB- 3 \ times 4 -RCB- -LSB- / math -RSB- + ... ?
How would you calculate -LSB- math -RSB- \ sum _ -LCB- n = 1 -RCB- ^ \ infty \ frac -LCB- 1 -RCB- -LCB- 2 ^ n -RCB- \ cdot \ frac -LCB- 1 -RCB- -LCB- n - \ frac45 -RCB- -LSB- / math -RSB- ?