# SageMath code for working with modular form 841.2.e.d


# Compute space of new eigenforms: 
from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(841, base_ring=CyclotomicField(14))
chi = DirichletCharacter(H, H._module([11]))
N = Newforms(chi, 2, names="a")

# select newform: 
traces = [12,0,0,4,-2,6,2,0]
f = next(g for g in N if [g.coefficient(i+1).trace() for i in range(8)] == traces)

# q-expansion: 
f.q_expansion() # note that sage often uses an isomorphic number field