zeta_em_choose_param hack: use fewer bernoulli numbers for zeta(0.5+Ni), N large
zeta_em_choose_param hack: use fewer bernoulli numbers for zeta(0.5+Ni), N large

pascalmolin/arb,argriffing/arb,fredrik-johansson/arb,argriffing/arb,pascalmolin/arb,pascalmolin/arb,argriffing/arb,fredrik-johansson/arb