Pyramid #22
Generating function
$$U_{22}(x, y) = \frac{- y - \sqrt{- 4 x + y^{2} - 2 y + 1} + 1}{2 x}$$
Explicit formula
$$T_{22}(n, m, k) = \frac{k {\binom{k + 2 n}{n}} {\binom{k + m + 2 n - 1}{m}}}{k + 2 n}$$
Data table
1 1 1 1 1 1 1
1 3 6 1 15 21 28
2 1 3 7 14 252 42
5 35 14 42 105 231 462
14 126 63 231 693 18018 42042
42 462 2772 12012 42042 126126 336336
132 1716 12012 6006 24024 816816 2450448
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