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Linnik's theorem

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Linnik's theorem in analytic number theory answers a natural question after Dirichlet's theorem on arithmetic progressions. It asserts that there exist positive c and L such that, if we denote p(a,d) the least prime in the arithmetic progression

Contents

a + n d ,  

where n runs through the positive integers and a and d are any given positive coprime integers with 1 ≤ ad - 1, then:

p ( a , d ) < c d L .

The theorem is named after Yuri Vladimirovich Linnik, who proved it in 1944. Although Linnik's proof showed c and L to be effectively computable, he provided no numerical values for them.

Properties

It is known that L ≤ 2 for almost all integers d.

On the generalized Riemann hypothesis it can be shown that

p ( a , d ) ( 1 + o ( 1 ) ) φ ( d ) 2 ln 2 d ,

where φ is the totient function.

It is also conjectured that:

p ( a , d ) < d 2 .

Bounds for L

The constant L is called Linnik's constant and the following table shows the progress that has been made on determining its size.

Moreover, in Heath-Brown's result the constant c is effectively computable.

References

Linnik's theorem Wikipedia