Solve the following:  $${{1}^{2}}+\left( {{1}^{2}}+{{2}^{2}} \right)+\left( {{1}^{2}}+{{2}^{2}}+{{3}^{2}} \right)+\cdots +\left( {{1}^{2}}+{{2}^{2}}+{{3}^{2}}+\cdots+{{20}^{2}} \right)$$． 
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