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18.03.2013

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, n n Sn = 2n2 + 3n. , .

: , , , , 2n2 + 3n = n/2(25 + 4(n - 1)) - n .

: 41.


1, 8, 22, 43,... - ( ) : 7, 14, 21,... . , 35351.

: (8 - 1 = 7, 22 - 8 = 14, 43 - 22 = 21 .. an - an - 1 = bn - 1, an = 35351, bn - 1 - 7 7). , , .

: 101.


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2009-2012 . " - !" - , . .
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