  We consider entanglement negativity for two disjoint intervals in 1+1
dimensional CFT in the limit of large central charge. As the two intervals get
close, the leading behavior of negativity is given by the logarithm of the
conformal block where a set of approximately null descendants appears in the
intermediate channel. We compute this quantity numerically and compare with
existing analytic methods which provide perturbative expansion in powers of the
cross-ratio.
