Cr−1n+2\mathrm{C}_{\mathrm{r}-1}^{\mathrm{n}+2}Cr−1n+2
C2r−12n+2C_{2 r-1}^{2 n+2}C2r−12n+2
Crn+2\mathrm{C}_{\mathrm{r}}^{\mathrm{n}+2}Crn+2
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