if you wish to have $250,000 in 30 years, how much mush be deposited weekly in an account that pays 6% compounded weekly? (50 weeks per year)

50 weeks in a year ???

mmmhhhh?

anyway I will go with that.
n = 30x50 = 1500
i = .06/50 = .0012
deposit = x

x( 1.0012^1500 - 1)/.0012 = 250000
you do the button-pushing

(I got $59.49 )

check by estimating:
payment appr. 240 a month monthly rate = .06/12 = .005
amount after 30 yrs
= 240(1.005^360 - 1)/.005
= appr $241 000
my answer is plausable.