Niven's constant

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In number theory, Niven's constant, named after Ivan Niven, is the largest exponent appearing in the prime factorization of any natural number n "on average". More precisely, if we define H(1) = 1 and H(n) = the largest exponent appearing in the unique prime factorization of each natural number n > 1, then Niven's constant is given by

$\lim_{n \to \infty} \frac{1}{n} \sum_{j=1}^n H(j) = \sum_{k=2}^\infty \frac{\zeta(k) - 1}{\zeta(k)} = 1.705211\dots \,$

where ζ(k) is the value of the Riemann zeta function at the point k (Niven, 1969).

In the same paper Niven also proved that

$\sum_{j=1}^n h(j) = n + c\sqrt{n} + o (\sqrt{n}) \,$

where h(1) = 1, h(n) = the smallest exponent appearing in the unique prime factorization of each natural number n > 1, o is little o notation, and the constant c is given by

$c = \frac{\zeta(\frac{3}{2})}{\zeta(3)}. \,$