Again, the formula is valid for "x" > 1, while "ρ" are the nontrivial zeros of the zeta function ordered according to their absolute value, and, again, the latter integral, taken with minus sign, is just the same sum, but over the trivial zeros. The first term li("x") is the usual logarithmic integral function; the expression li("x""ρ") in the second term should be considered as Ei(ρ ln "x"), where Ei is the analytic continuation of the exponential integral function from negative reals to the complex plane with branch cut along the positive reals.