Express the geometric sum using summation notation. \[ 1+4+16+64+256+1024+4096+16384 \]

Step 1 ：This is a geometric series where each term is 4 times the previous term. The first term is 1 and the common ratio is 4. The series has 8 terms.

Step 2 ：In general, the nth term of a geometric series with first term a and common ratio r is given by a*r^(n-1).

Step 3 ：So, we can express this series using summation notation as the sum from n=1 to 8 of 4^(n-1).

Step 4 ：Final Answer: The geometric sum can be expressed using summation notation as \(\boxed{\sum_{n=1}^{8} 4^{n-1}}\)