Dimensions

J.-I. Igusa determined in the 1960s the dimension of the space of scalar-valued cusp forms on $\Sp(4,\Z)$. R. Tsushima gave in the 1980s formulas for the dimensions of the spaces of vector-valued cusp forms of degree $2$ and extended this to a subgroup of $\Gamma_2[2]$, see the references in [2] and [3]. Bergström extended this to $\Gamma_2[2]$ together with the action of $\Sp(4,\mathbb{Z}/2)$ (unpublished).

Show dimensions for level 1 level 2: $s[6]$ level 2: $s[5,1]$ level 2: $s[4,2]$ level 2: $s[4,1,1]$ level 2: $s[3,3]$ level 2: $s[3,2,1]$ level 2: $s[3,1,1,1]$ level 2: $s[2,2,2]$ level 2: $s[2,2,1,1]$ level 2: $s[2,1,1,1,1]$ level 2: $s[1,1,1,1,1,1]$