Editing Weierstrass factorization theorem (section)

===Existence of entire function with specified zeroes===
Let <math>\{a_n\}</math> be a sequence of non-zero [[complex number]]s such that <math>|a_n|\to\infty</math>.
If <math>\{p_n\}</math> is any sequence of nonnegative integers such that for all <math>r>0</math>,
: <math> \sum_{n=1}^\infty \left( r/|a_n|\right)^{1+p_n} < \infty,</math>
then the function
: <math>E(z) = \prod_{n=1}^\infty E_{p_n}(z/a_n)</math>
is entire with zeros only at points <math>a_n</math>.<ref name="rudin"/> If a number <math>z_0</math> occurs in the sequence <math>\{a_n\}</math> exactly {{math|''m''}} times, then the function {{math|''E''}} has a zero at <math>z=z_0</math> of multiplicity {{math|''m''}}.

* The sequence <math>\{p_n\}</math> in the statement of the theorem always exists. For example, we could always take <math>p_n=n</math> and have the convergence. Such a sequence is not unique: changing it at finite number of positions, or taking another sequence {{math|''p''′<sub>''n''</sub> ≥ ''p''<sub>''n''</sub>}}, will not break the convergence.
* The theorem generalizes to the following: [[sequences]] in [[open subsets]] (and hence [[Region (mathematics)|regions]]) of the [[Riemann sphere]] have associated functions that are [[Holomorphic function|holomorphic]] in those subsets and have zeroes at the points of the sequence.<ref name="rudin"/>