Syntax

stolen from Matt cool curly brace thing $|x|=\{\begin{array}{l}x\text{ for }x>0\\ 0\text{ for }x=0\\ -x\text{ for }x<0\end{array}$

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DESMOS GRAPH

left=0; right=100;
top=10; bottom=-10;
---
y=\sin(x)
y=\cos(x)

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\begin{document}
\begin{tikzpicture}[
    level distance=2cm,
    level 1/.style={sibling distance=4cm},
    level 2/.style={sibling distance=3cm},
    level 3/.style={sibling distance=2.5cm},
    level 4/.style={sibling distance=2cm}
]
\node[circle,draw] {$n$}
    child {node[circle,draw] {$k$}}
    child {node[circle,draw] {$\frac{n}{2}$}
        child {node[circle,draw] {$k$}}
        child {node[circle,draw] {$\frac{n}{4}$}
            child {node[circle,draw] {$k$}}
            child {node[circle,draw] {$\frac{n}{2^a}$}
                child {node[circle,draw] {$1$}}
                child {node[circle,draw] {$\cdots$}}
            }
        }
    };
\end{tikzpicture}
\end{document}

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Arthur Schopenhauer

A constant flow of thoughts expressed by other people can stop and deaden your own thought and your own initiative.