Imy answer is,
$$\require{action}\require{enclose}\toggle{\enclose{roundedbox}{\text{ Click here to toggle grid }}}{\enclose{roundedbox}{\text{ Click here to toggle grid }}\begin{array}{|c|c|}\hline\begin{array}{c}\bbox[pink]{\begin{array}{c|c|c}{\textbf0} & \textbf1 & 2 \\\hline\textbf1 & 2 & \textbf4 \\\hline 2 & 4& \textbf8 \\\hline \ \textbf3\ & \ \textbf7\ & 15 \end{array}}\\\hline\bbox[cyan]{\begin{array}{c|c|c}\text{-4}\ & 12\ & 28 \\\hline 12 & \textbf{28} & 44 \end{array}} \end{array} & \begin{array}{c} \bbox[yellow]{ \begin{array}{c|c|c} 3 & \textbf5 & 8 \\\hline 6 & 10 & \textbf{16} \\\hline 12 & \textbf{20} & 32 \end{array}}\\\hline \begin{array}{c|c|c} \textbf6 & 14 & 30 \\\hline \text{-8} & \textbf{24} & 56 \\\hline 24 & 56 & \textbf{88} \end{array} \end{array} \\\hline \end{array}}\endtoggle$$
Top left (pink) is sum of top and left
Top right (yellow) is sum of two left ones
Bottom left (cyan) is left +16
Bottom right (white) is three to the left doubled
original format:
I am not on a computer so sorry for formatting.
my answer is, where _ seperate_ separate cells and ' seperates separates groups, and bold is the last row in a group,
0_1_2'3_5_8
1_2_4'6_10_16.
2_4_8'12_20_32
3_7_15'6_14_30
-4_12_28'-8_24_56
12_28_44'24_56_88
Top left is sum of top and left Top right is sum of two left ones Bottom left is left +16 Bottom right is three to the left doubled
