  Recently Alday, Gaiotto and Tachikawa have proposed relation between 2- and
4-dimensional conformal field theories. The relation implies that the Nekrasov
partition functions of N=2 superconformal gauge theories are equal to conformal
blocks associated with the conformal algebra. Likewise, a counterpart in pure
super Yang-Mills theory exists in conformal field theory. We propose a simple
relation between the Shapovalov matrix of the W_3-algebra and the Nekrasov
partition function of N=2 SU(3) Yang-Mills theory.
