Question 366779
{{{f(0)=2}}}
{{{f(f(0))=f(2)=4}}}
{{{f(f(f(0)))=f(f(2))=f(4)=2}}}
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{{{f(2)=4}}}
{{{f(f(2))=f(4)=2}}}
{{{f(f(f(2)))=f(f(4))=f(2)=4}}}
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Putting it all together,
{{{f(f(f(0)))+f(f(f(2)))=2+4}}}
{{{highlight(f(f(f(0)))+f(f(f(2)))=6)}}}