  In an earlier paper, we discussed the probability that the determinant of a
matrix undergoes the least change upon perturbation of one of its elements,
provided that most or all of the elements of the matrix are chosen at random
and that the randomly chosen elements have a fixed probability of being
non-zero. In this paper, we derive approximate formulas for that probability by
assuming that the terms in the permanent of a matrix are independent of one
another, and we apply that assumption to several classes of matrices. In the
course of deriving those formulas, we identified several integer sequences that
are not listed on Sloane's Web site.
