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7
2013 HMMT Algebra #7: Seven-Fold Summation
2013 HMMT Algebra #7: Seven-Fold Summation
Source:
February 17, 2013
HMMT
Problem Statement
Compute
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\sum_{a_1=0}^\infty\sum_{a_2=0}^\infty\cdots\sum_{a_7=0}^\infty\dfrac{a_1+a_2+\cdots+a_7}{3^{a_1+a_2+\cdots+a_7}}.
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