Change of Base Q3

Given that \(\sum\limits_{r=1}^{n}{r}=\frac{n}{2}(n+1)\), \(\sum\limits_{r=1}^{n}{{{r}^{2}}}=\frac{1}{6}n\left( n+1 \right)\left( 2n+1 \right)\) and \(\sum\limits_{r=1}^{n}{{{r}^{3}}}=\frac{1}{4}{{n}^{2}}{{\left( n+1 \right)}^{2}}={{\left[ \frac{1}{2}n\left( n+1 \right) \right]}^{2}}\).

Find, in terms of \(n\),

1. \(\sum\limits_{r=0}^{n}{\left( {{r}^{2}}+r-n \right)}\),
2. \(\sum\limits_{r=1}^{20}{\left( 2{{r}^{2}}-1 \right)\left( r+1 \right)}\).