notasi sigma yang menyatakan 1/27+1/9+1/3+...+729 adalah *penting banget mksh

3^-3 = 3^(1-4)
3^-2 = 3^(2-4)
3^-1 = 3^(3-4)
...
3^6 = 3^(10-4)
------------------------+
sigma[n=1..10] (3^(n-4))