sage:from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(4140, base_ring=CyclotomicField(2))
chi = DirichletCharacter(H, H._module([0, 0, 1, 0]))
N = Newforms(chi, 2, names="a")
magma://Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
chi := DirichletCharacter("4140.829");
S:= CuspForms(chi, 2);
N := Newforms(S);
This newform subspace can be constructed as the kernel of the linear operator
T712+49T710+867T78+6563T76+18808T74+9648T72+1296
acting on S2new(4140,[χ]).