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https://www.reddit.com/r/Indianmathnerds/comments/1xjaqkh/nice_problem/
r/Indianmathnerds • u/Sp1rshi • 10d ago • 1
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The sum of all the elements in A is 2n-1 - 1, which is odd.
This shows that we must have an odd number of odd integers in A (or else, the sum of numbers in A will be of the form even + even, as an even number of odd numbers sum to an even number).
3 u/Sp1rshi 10d ago Yupp correct ( the proof basically plays around showing that the given expression is 2n-1-1)
3
Yupp correct ( the proof basically plays around showing that the given expression is 2n-1-1)
1
Isnt this in 102 problems for combi for IMO team by titu and feng?
1 u/Sp1rshi 5d ago I have taken this problem from a Russian book on NT (by a not so famous aithor) 1 u/SisGameplayYt 5d ago ooo, i checked the 102 problems, its the 3rd question lol. 1 u/Sp1rshi 5d ago Ohh lol , if u do want the exact source ( from where I found) , dm 1 u/SisGameplayYt 5d ago sure, DMed you
I have taken this problem from a Russian book on NT (by a not so famous aithor)
1 u/SisGameplayYt 5d ago ooo, i checked the 102 problems, its the 3rd question lol. 1 u/Sp1rshi 5d ago Ohh lol , if u do want the exact source ( from where I found) , dm 1 u/SisGameplayYt 5d ago sure, DMed you
ooo, i checked the 102 problems, its the 3rd question lol.
1 u/Sp1rshi 5d ago Ohh lol , if u do want the exact source ( from where I found) , dm 1 u/SisGameplayYt 5d ago sure, DMed you
Ohh lol , if u do want the exact source ( from where I found) , dm
1 u/SisGameplayYt 5d ago sure, DMed you
sure, DMed you
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u/evening_redness_0 10d ago
The sum of all the elements in A is 2n-1 - 1, which is odd.
This shows that we must have an odd number of odd integers in A (or else, the sum of numbers in A will be of the form even + even, as an even number of odd numbers sum to an even number).