$$U_{186}(x, y) = \frac{- x + \sqrt{x^{2} + 2 x + 4 y + 1} - 1}{2 y}$$

$$T_{186}(n, m, k) = \frac{\left(-1\right)^{- m + n} k {\binom{k + m + n - 1}{n}} {\binom{k + 2 m + n - 1}{m}}}{k + m}$$