Question Number 211986 by Spillover last updated on 26/Sep/24
Commented by MathematicalUser2357 last updated on 26/Sep/24
$$=\underset{{r}=\mathrm{1}} {\overset{{m}−\mathrm{1}} {\sum}}\frac{\mathrm{2}{r}^{\mathrm{2}} −{r}\left({m}−\mathrm{2}\right)+\mathrm{1}}{\left({m}−{r}\right)\:_{{m}} {C}_{{r}} } \\ $$