Puff Daddy wants to be sure that his lavish spending habits do not leave him bankrupt, so he will purchase an annuity. The annuity will make 21 semiannual payments of the form $6500,13000,6500,13000,\ldots$, with the first payment coming 6 months after he purchases the annuity. If the annuity pays an interest rate of 7.8 percent convertible semiannually, how much should Puff Daddy pay for this annuity?

Answer = dollars.