To illustrate future payments of an annuity where the
first monthly payment is $2,500 compounded annually by 3% -- I know
how to calculate what the payment will look like say in the 10th year
which is $40,317, with this formula :

P = future value
C = initial deposit
r = interest rate (expressed as a fraction: eg. 0.06)
n = # of times per year interest is compounded
t = number of years invested

But I can't figure out how to calculate the total amount paid in the
10th year which is $425,761. I got the answer by building a
table and summing the yearly payments as follows - but, I want a formula that will return the answer of $425,761 with the variables I have.

$2,500 3% $30,000 $30,000
$2,575 $30,900 $60,900
$2,652 $31,827 $125,509
$2,732 $32,782 $159,274
$2,814 $33,765 $194,052
$2,898 $34,778 $229,874
$2,985 $35,822 $266,770
$3,075 $36,896 $304,773
$3,167 $38,003 $343,916
$3,262 $39,143 $384,234
$3,360 $40,317 $425,761

Thanks,

John