The integral on the right is standard and goes by many names: it is a particular case of a Bose–Einstein integral, the polylogarithm, or the Riemann zeta function ζ ζ ( s ) . The value of the integral is Γ Γ ( 4 ) ζ ζ ( 4 ) = π π 4 15 (where Γ Γ ( s ) is the Gamma function), giving the result that, for a perfect blackbody surface: M ∘ ∘ = σ σ T 4 , σ σ = 2 π π 5 k 4 15 c 2 h 3 = π π 2 k 4 60 ℏ ℏ 3 c 2 .