This is LaTeX code:

[latex]
At^{\left( 1 \right)} = 2t^{\left( 1 \right)} ,At^{\left( 2 \right)} = t^{\left( 2 \right)} ,At^{\left( 3 \right)} = t^{\left( 2 \right)} + t^{\left( 3 \right)}
[/latex]