How do I sum a figure derived from a row of cells

Start with a row of numbers. "x"

I wish to calculate the sum of the results of an operation applied to the numbers - for example, sum the squares of the numbers. "f(x)"

Is it possible to combine the summation with the operation without having a separate cell showing "f(x)"?

i.e. sum(f(A1):f(A21))

thanks,

S.