magma:// Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
chi := DirichletCharacter("239.1");
S:= CuspForms(chi, 4);
N := Newforms(S);
sage:from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(239, base_ring=CyclotomicField(2))
chi = DirichletCharacter(H, H._module([0]))
N = Newforms(chi, 4, names="a")
This newform subspace can be constructed as the kernel of the linear operator
\( T_{2}^{37} - 4 T_{2}^{36} - 225 T_{2}^{35} + 891 T_{2}^{34} + 22979 T_{2}^{33} - 89996 T_{2}^{32} + \cdots + 8610703477760 \)
acting on \(S_{4}^{\mathrm{new}}(\Gamma_0(239))\).