$$U_{273}(x, y) = x^{2} + y^{2} + y$$

$$T_{273}(n, m, k) = \left(\frac{\left(-1\right)^{n}}{2} + \frac{1}{2}\right) {\binom{k}{\frac{n}{2}}} {\binom{k - \frac{n}{2}}{- k + m + \frac{n}{2}}}$$