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[TEX]1)2A{n}^{3}+6A{n}^{2}=P_{n+1}[/TEX]
[TEX]2)P_{n+5}=240A{n+3}^{k+3}.P_{n-k}[/TEX]
[TEX]3)P_{n+5}=15A{n+1}^{k}.P_{n+4-k}[/TEX]
[TEX]2)P_{n+5}=240A{n+3}^{k+3}.P_{n-k}[/TEX]
[TEX]3)P_{n+5}=15A{n+1}^{k}.P_{n+4-k}[/TEX]