Expression 2: psi left parenthesis, "x" , right parenthesis equals natural log left parenthesis, Start product from "k" equals 1 to "x" , end product, left brace, Pi left parenthesis, "k" , right parenthesis equals 1 : "k" Superscript, floor left parenthesis, log Subscript, "k" , Baseline left parenthesis, "x" , right parenthesis , right parenthesis , Baseline , 1 , right brace , right parenthesisψx=lnx∏k=1Πk=1:kfloorlogkx,1
2
Wolfram gives the second Chebyshev function as the natural log of the least common multiple of numbers in the range 1 to x, is this not the function you're after?