Difference between revisions of "2008 AIME II Problems/Problem 6"
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Latest revision as of 22:34, 4 July 2013
Problem
The sequence is defined by The sequence is defined by Find .
Solution
Rearranging the definitions, we have from which it follows that and . These recursions, and , respectively, correspond to the explicit functions and (after applying our initial conditions). It follows that .
From this, we can determine that the sequence corresponds to the triangular numbers.
See also
2008 AIME II (Problems • Answer Key • Resources) | ||
Preceded by Problem 5 |
Followed by Problem 7 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 | ||
All AIME Problems and Solutions |
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