Question 83820
The ratio r is the factor to get from term to term. So 
r=nth term/(n-1) term
{{{r=8/4=2}}}
{{{r=2}}}
The sequence doubles each term, so the sequence is {{{2^n}}}
So the 24th term is 
{{{2^23=8388608}}}(n=23 zero is the 1st term)
The sum of a geometric series is 
{{{S=a(1-r^n)/(1-r)}}}where a=1
{{{S=(1-2^10)/(1-2)}}}
{{{S=(1-1024)/(-1)}}}
{{{S=1023}}}
So the sum of the first ten terms is 1,023