A sequence with a_1 = 1 is defined by the recurrence relation a_{n+1} = 2^n + a_n for all natural numbers n. If a_{23} = p, then what is p?
Note that the first few terms of the sequence are :
1, 3 , 7 , 15 , 31 , 63 , 127 .....
The terms are 2^n - 1 where n = the nth term
a23 = p = 2^23 - 1 = 8388607
