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I. 2. 3 - - V 



I. When n is even and *.• v even it is of this form 



„. n — ^ — 2 - - n — 2. «. K + 2 - - « + u — 2 



+ _ — . _ 



I. 2. 'i - - V 



2 2 2 2 2 V 



= ± n. «— 2. «— 4 - - to — terms 



2 



2. 3 



2i 11 V . 



The lign is + or — according as — or — ^ — is even or odd. 



If 



