Helium is thought of as not being solvable by symbolic methods for its first ionization energy.
As in Newtonian mechanics, no system that consists of more than two particles can be solved with an exact analytical mathematical approach (see 3-body problem) and helium is no exception. Thus, numerical mathematical methods are required, even to solve the system of one nucleus and two electrons.
- https://en.m.wikipedia.org/wiki/Helium As of August Second of 2019
However that is not true. Applying what I call Genesis principles of how the universe is constructed, together with realizing that the probability distribution of both of its two electrons is spherical because of the symmetry and purtebation characteristics of the problem, the first ionization energy of Helium is solved within 0.3% - basically fully accounting fully to it's measured value.
The Solution to the First Ionization Energy With Symbolic Calculations
The attached PDF file solves Helium to 0.3% as referenced below, just using integral calculus.