# SageMath code for working with modular form 12996.2.a.z


# Compute space of new eigenforms: 
from sage.modular.dirichlet import DirichletCharacter
H = DirichletGroup(12996, base_ring=CyclotomicField(2))
chi = DirichletCharacter(H, H._module([0, 0, 0]))
N = Newforms(chi, 2, names="a")

# select newform: 
traces = [2,0,0,0,1,0,0,0,0,0,6,0,-9,0,0,0,3,0,0,0,0,0,-14,0,-7,0,0,0,
-17,0,6,0,0,0,10,0,-1,0,0,0,-11,0,4,0,0,0,-4,0,26,0,0,0,7,0,-2,0,0,0,10,
0,9,0,0,0,-2,0,6,0,0,0,-18,0,7,0,0,0,-20,0,12,0,0,0,-12,0,14,0,0,0,-15,
0,10,0,0,0,0,0,9,0,0,0]
f = next(g for g in N if [g.coefficient(i+1).trace() for i in range(None)] == traces)

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