Difference between revisions of "2021 AIME I Problems/Problem 10"

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==Problem==
 
==Problem==
These problems will not be available until the 2021 AIME I is released on Wednesday, March 10, 2021.
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Consider the sequence <math>(a_k)_{k\ge 1}</math> of positive rational numbers defined by <math>a_1 = \frac{2020}{2021}</math> and for <math>k\ge 1</math>, if <math>a_k = \frac{m}{n}</math> for relatively prime positive integers <math>m</math> and <math>n</math>, then
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<cmath>a_{k+1} = \frac{m + 18}{n+19}.</cmath>Determine the sum of all positive integers <math>j</math> such that the rational number <math>a_j</math> can be written in the form <math>\frac{t}{t+1}</math> for some positive integer <math>t</math>.
  
 
==Solution==
 
==Solution==

Revision as of 16:49, 11 March 2021

Problem

Consider the sequence $(a_k)_{k\ge 1}$ of positive rational numbers defined by $a_1 = \frac{2020}{2021}$ and for $k\ge 1$, if $a_k = \frac{m}{n}$ for relatively prime positive integers $m$ and $n$, then

\[a_{k+1} = \frac{m + 18}{n+19}.\]Determine the sum of all positive integers $j$ such that the rational number $a_j$ can be written in the form $\frac{t}{t+1}$ for some positive integer $t$.

Solution

See also

2021 AIME I (ProblemsAnswer KeyResources)
Preceded by
Problem 9
Followed by
Problem 11
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
All AIME Problems and Solutions

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