Niven's constant

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 a natural number n > 1, then Niven's constant is given by

$\lim _{n\to \infty }{\frac {1}{n}}\sum _{j=1}^{n}H(j)=1+\sum _{k=2}^{\infty }(1-{\frac {1}{\zeta (k)}})=1.705211\dots \,$

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

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

and consequently that

$\lim _{n\to \infty }{\frac {1}{n}}\sum _{j=1}^{n}h(j)=1.$

References

• Niven, Ivan M. (1969). "Averages of Exponents in Factoring Integers". Proceedings of the American Mathematical Society. 22 (2): 356–360. doi:10.2307/2037055. Retrieved 2007-03-08. {{cite journal}}: Unknown parameter |month= ignored (help)
• Steven R. Finch, Mathematical Constants (Encyclopedia of Mathematics and its Applications), Cambridge University Press, 2003

External links

• Weisstein, Eric W. "Niven's Constant". MathWorld.
• Sloane, N. J. A. (ed.). "Sequence A033150". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation.