The amortization formula applies.
 A = P*(r/n)/(1 -(1 +r/n)^-(nt))
where
 A is the payment in each compounding period (820)
 P is the principal amount (present value)
 r is the annual interest rate (.05)
 n is the number of compoundings per year (2)
 t is the number of years (14)
Filling in the numbers, we have
 820 = P*(.05/2)/(1 -(1 +.05/2)^-(2*14))
 820 = .025P/(1 -1.025^-28)
 P = 820(1 -1.025^-28)/.025
 P ≈ 16,371.21
The present value of that string of payments is $16,371.21.