Answer:
$280,557.35
Explanation:
Assuming your withdrawals are at the beginning of the month, the present value of the sum of those withdrawals is ...
PV = P(1 -(1 +r/n)^(-nt))/(1 -(1 +r/n)^-1)
PV = P(1 +n/r)(1 -(1 +r/n)^(-nt))
for monthly withdrawal P, n=12, r=.06, t=20.
PV = $2000(1 +12/0.06)(1 -1.005^-240) = $280,557.35
You need $280,557.35 in your retirement account to support the planned set of payments.