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∑ n = 1 50 ( 2 n − 1 ) ( n + 2 ) 2 = 1 ⋅ 3. 2 + 3. ⋅ 4 2 + 5 ⋅ 5 2 + ⋯ + 99 ⋅ 52 2 = ? \总和_ {n = 1} ^{50}{\离开(2 n - 1 \右){\离开(n + 2 \右)}^ {2}}= 1 \ cdot {3} ^ {2} + 3 \ cdot {4} ^ {2} + 5 \ cdot {5} ^ {2} + \ cdots + 99 \ cdot {52} ^ {2} = \ ? n=1∑50(2n−1)(n+2)2=1⋅3.2+3.⋅42+5⋅52+⋯+99⋅522=?
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