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          |  | Volume 10, Issue 1, Article 11 |  |   
          |  |  |  |  |  |  | Necessary and Sufficient Conditions for Joint Lower and Upper Estimates
 
 
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          |  |  | Authors: | Laszlo Leindler, |  |   
          |  |  | Keywords: | Sequences and series, inequalities, power-monotonicity. |  |   
          |  |  | Date Received: | 28/02/08 |  |   
          |  |  | Date Accepted: | 17/01/09 |  |   
          |  |  | Subject Codes: | 40A30, 40A99. |  |   
          |  |  | Editors: | Sever S. Dragomir, |  |   
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          |  |  | Abstract: |  Necessary and sufficient conditions are given for joint lower and upper estimates of the following sums   and  . An application of the results yields necessary and sufficient conditions for a pleasant and useful lemma of Sagher. |   
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