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This is the inverse to Problem 1471. Index of a Rational number

The first ten positive rational numbers under the enumeration using cantors diagonalization argument are 1/1, 2/1, 1/2, 3/1, 2/2, 1/3, 4/1, 3/2, 2/3, 1/4.

Find the index of a positive rational number enumerated in this manner, i.e. the 6th rational number is 1/3.

40 correct solutions
39 incorrect solutions

Last solution submitted on Feb 10, 2016

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1 Comment

Richard
on 28 Sep 2015

I thought we had to discount all the equivalent fractions (like 2/2) so I wrote this horrible cheat. How embarrassing.

1 Comment