Solutions to equilibrium sequences of irrotational binary polytropic stars in Newtonian gravity are expanded in a power of = a0/R, where R and a0 are the orbital separation of the binary system and the radius of each star for R = ∞. For each order of , we should solve ordinary differential equations for arbitrary polytropic indices n. We show solutions for polytropic indices n = 0.5, 1, 1.5 and 2 up to 6 orders. Our semi-analytic solutions can be used to check the validity of numerical solutions. PACS number(s): 04.30. Db, 04.25.Dm, 97.80.Fk