In this paper we give an explicit Fourier expansion of the Eisenstein series on certain quaternion unitary groups of degree 2 by means of Shimura's method. Moreover using an explicit formula of the Fourier coefficients of holomorphic Eisenstein series and Oda's lifted cusp forms, we give some numerical examples.
Yoshikazu HIRAI. "On Eisenstein series on quaternion unitary groups of degree 2." J. Math. Soc. Japan 51 (1) 93 - 128, January, 1999. https://doi.org/10.2969/jmsj/05110093