\begin{tikzpicture}%[scale = .79]
%[scale=.5]
%[font=\footnotesize] 
 \matrix(m) [matrix of math nodes,row sep={1.2em,between origins},column sep={1.35em,between origins},nodes in empty cells]{
 -1&&-1&&-1&&-1&&-1&&-1&&&&&&&&&&&\\
&\mathbf{0}&&\mathbf{0}&&\mathbf{0}&&\mathbf{0}&&\mathbf{0}&&\mathbf{0}&&&&&&&&&&&\\
&&1&&1&&1&&1&&1&&1&&&&&&&&&&\\
&&&1&&2&&6&&1&&2&&6&&&&&&&&&\\
&&&&\mathbf{1}&&\mathbf{11}&&\mathbf{5}&&\mathbf{1}&&\mathbf{11}&&\mathbf{5}&&&&&&&&\\
&&&&&5&&9&&4&&5&&9&&4&&&&&&&\\
&&&&&&4&&7&&19&&4&&7&&19&&&&&&\\
&&&&&&&\mathbf{3}&&\mathbf{33}&&\mathbf{15}&&\mathbf{3}&&\mathbf{33}&&\mathbf{15}&&&&&\\
&&&&&&&&14&&26&&11&&14&&26&&11&&&&\\
&&&&&&&&&11&&19&&51&&11&&19&&51&&&\\
&&&&&&&&&&\mathbf{8}&&\mathbf{88}&&\mathbf{40}&&\mathbf{8}&&\mathbf{88}&&\mathbf{40}&&\\
&&&&&&&&&&&37&&69&&29&&37&&69&&29&\\
&&&&&&&&&&&&29&&50&&134&&29&&50&&134\\
&&&&&&&&&&&&&&&
\node[rotate=-6.5,shift={(-0.034cm,-0.08cm)}]  {\ddots};&&&&&&\node[rotate=-6.5,shift={(-0.034cm,-0.08cm)}]  {\ddots};\\
};

\draw[opacity=0,rounded corners,fill=myblue,fill opacity=0.15] (m-1-1.south west) -- (m-13-13.south west) -- (m-13-19.south west) -- (m-1-7.south west) -- cycle;

\draw ($(m-3-3)+(0,0.6125cm)$) node[ellipse, minimum height=2cm,minimum width=0.65cm,draw,semithick,opacity=0.5] {};
\draw ($(m-6-6)+(0,0.6125cm)$) node[ellipse, minimum height=2cm,minimum width=0.65cm,draw,semithick,opacity=0.5] {};
\draw ($(m-9-9)+(0,0.6125cm)$) node[ellipse, minimum height=2cm,minimum width=0.65cm,draw,semithick,opacity=0.5] {};
\draw ($(m-12-12)+(0,0.6125cm)$) node[ellipse, minimum height=2cm,minimum width=0.65cm,draw,semithick,opacity=0.5] {};

\draw (m-2-1) node[shift={(-1.5cm,0cm)}]{$s_0=2$};
\draw (m-5-4) node[shift={(-1.5cm,0cm)}]{$s_1=3$};
\draw (m-8-7) node[shift={(-1.5cm,0cm)}]{$s_2=7$};
\draw (m-11-10) node[shift={(-1.5cm,0cm)}]{$s_3=18$};


%\fill[myred,opacity=0.3] (m-1-9) circle (0.25cm);
%\fill[myred,opacity=0.3] (m-7-15) circle (0.25cm);
%\fill[myred,opacity=0.3] (m-13-21) circle (0.25cm);

%\fill[mygreen,opacity=0.3] (m-2-8) circle (0.25cm);
%\fill[mygreen,opacity=0.3] (m-5-11) circle (0.25cm);
%\fill[mygreen,opacity=0.3] (m-8-14) circle (0.25cm);
%\fill[mygreen,opacity=0.3] (m-11-17) circle (0.25cm);
\end{tikzpicture}