Generating function
$$U_{1188}(x, y) = \frac{\frac{2 x}{\left(1 - y\right)^{3}} + \sqrt{\frac{4 x^{2}}{\left(1 - y\right)^{6}} + 1}}{\left(1 - y\right)^{3}}$$
Explicit formula
$$Tsqrt2(n, k) = \begin{cases}\frac {k \binom{n+j}{n} \binom{2n+2j}{n+j}} {\binom{2j}{j} {n+k}} &\text{if n+k even, where j =} \frac{n+k} {2},\\\frac {k \binom{n+j}{n} \binom{2n+2j}{n+j}} {\binom{2j}{j} {n+k}} &\text{if n+k odd, where j =} \frac{n+k+1} {2},\\\end{cases} $$$$T_{1188}(n, m, k) = k \operatorname{Tsqrt_{2}}{\left(n,k \right)} {\binom{3 k + m + 3 n - 1}{m}}$$
Data table
1 3 6 1 15 21 28
2 12 42 112 252 504 924
2 18 9 33 99 2574 6006
0 0 0 0 0 0 0
-2 -30 -240 -1360 -6120 -23256 -77520
0 0 0 0 0 0 0
4 84 924 7084 42504 212520 920920
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