(1/1+(4/n))(4/n)+(1/1+(8/n))(4/n)+(1/1+(12/n))(4/n)+....+(1/1+(4n/n))(4/n)

Question

is a right Riemann Sum for a certain definite integral.
Integral 1 to b, f(x) dx.
using a partition of the interval [1,b] into n subintervals of equal length.
Then the upper limit of integration must be: b=?
and the integrand must be function f(x)=?