Open and solved problems about the abc conjecture

What is the abc conjecture | Open and solved problems | Consequences | The algorithm

Number occurance

If you create a list of abc triples, you might notice the same c appears in multiple triples. Some appear only once, others two times, and others even more. We know for every n there is a c that appears in n triples. But what is the smallest c that occurs in 2 triples? what is the smallest that appears in 3 triples? And 4? The same is known for b, but again we do not know what the smallest b is that occurs in n triples.

We know that every a appears in infinitely many triples.

Difference of a and b

Which values appear for b - a, when a, b and c are an abc triple? Do some values never appear? Do some values appear more often than others?

Small triples

There are infinitely many triples, but how much are there with c < n? And for how many triples is b less than 2a?

Non-divisible numbers

When you have an abc triple, a, b or c is divisible by 2. Is there for every n an abc triple so a, b and c are not divisible by 3, 4, 5, ..., n? What is the smallest triple when n = 13?

Abc twins

Two triples are called a twin when both triples have the same c and the same radical. In this case, the triples also have the same quality. Can we find infinitely many of these twins?

Non-abc triples

If a + b = c, a and b are coprime and rad(abc) < c we have an abc triple. We can also look at non-abc triples where the radical may be bigger than c, so q < 1. Can we construct a sequence so q converges to 1/3?

Wim Voorn recently solved this problem by considering discovering there must be infinitely many squarefree triples of the form x, x+1, 2x+1.


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