Magma version V2.30-1
discriminant of the model of 21.b: [ <2, 3>, <3, 4> ]
(a) Frobenius polynomials agree with the prediction at all 60 primes 5 <= p < 300
(b) #J(F_5) = 21 and J(Q)_tors = Z/21
ALL_CHECKS_PASSED