Growth Rates - Question seems easy but answer doesn't make sense to me.?

You buy a set of encyclopedias. One per week. The first one only costs you $1.00, the second week it will double to $2.00, the third week it will double again to $4.00 and so on. Figure out the total amount of money you have spent at the end of each week. My calculations are: Week 1: 1.00, Week 2: $2.00 + $1.00 = $3.00, Week 3: $4.00 +$3.00 = $7.00 etc. I end up with a very large amount. After the question we are supposed to chart this on a graph but the graph only goes up to $200.00. This does not make sense to me. Help!