Three interesting infinite series by Mark Frauenfelder from on 2019-04-02 18:01 (#4CB6H) Numberphile takes a look at three interesting infinite series. The first is 1 + 1/2 + 1/4 + 1/8 ... which equals 2. The second is 1 + 1/2 + 1/3 + 1/4 + 1/5 ... which equals infinity. The third is 1 + (1/2)2 + (1/3)2 + (1/4)2... which I2/6