中!

bsically if we have an estimation for Chebyshev constant with:

pi(x) < C x/ln x

then  pi(x) * ln x < C * x    =>    x^pi(x) < (e^C)^x.

So we need to show 2*ln2 = 1.38629436+ is a good Chebyshev constant. Actually, there are proofs that 1.256 is a good Chebyshev constant.