Exact sparse monomial columns of the Euler differential matrix.
The nested polynomial associated with a monomial in two variables is the nested monomial with
outer exponent m 0 and inner exponent m 1.
For the monomial equation with outer and inner exponents s and t, the closed-form operator
sends the pair (monomial, 0) with exponents m, n to a single monomial with coefficient
n - t.
For the monomial equation with outer and inner exponents s and t, the closed-form operator
sends the pair (0, monomial) with exponents m, n to a single monomial with coefficient
s - m.
The closed-form operator of a monomial equation applied to a radial monomial pair is a single monomial, whose coefficient is the degree of the radial pair's homogeneous factor plus two minus the total degree of the equation.