Generating function
$$U_{1207}(x, y) = \frac{8 y^{6} \left(- \frac{x \left(1 - \sqrt{1 - 4 y}\right)}{y} - \sqrt{- \frac{2 x \left(1 - \sqrt{1 - 4 y}\right)}{y} + 1} + 1\right)^{3}}{x^{6} \left(1 - \sqrt{1 - 4 y}\right)^{6}}$$
Explicit formula
$$T_{1207}(n, m, k) = \frac{3 k n {\binom{6 k + 2 n}{n}} {\binom{2 m + n - 1}{m}}}{\left(3 k + n\right) \left(m + n\right)}$$
Data table
nan 0 0 0 0 0 0
6 6 12 3 84 252 792
27 54 135 378 1134 3564 11583
11 33 99 308 99 3267 11011
429 1716 6006 20592 70785 245388 858858
1638 819 3276 12285 45045 1639638 596232
6188 37128 167076 68068 2654652 10135944 38291344
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