Some examples of Niven numbers are 8, 12, 180, and 4050. The set of Niven numbers is infinite since any positive integral power of 10 is a Niven number. Even though a variety of ideas, results and… Expand

A Niven number is a positive integer that is divisible by its digital sum. That is, if n is an integer and s(n) denotes the digital sum of n, then n is a Niven number if and only if sin) is a factor… Expand

A Niven number is a positive integer which is divisible by its digital sum. A discussion of the possibility of an asymptotic formula for N(x) is given. Here, N(x) denotes the nmber of Niven numbers… Expand

INTRODUCTION In [1] the concept of a Niven number was introduced with the following definition. Definition: A positive integer is called a Niven number if it is divisible by its digital sum. Various… Expand

For a nonnegative integer k, let s(k) denote the digital sum of k. In [1], Cheo and Yien prove that, for a nonnegative integer x, x 1 (1.1) £ s(k) = (4.5)a: log x + 0(x) . fc=o Here 0(f(x)) is the… Expand

Stiffly stable linear k-step methods of order k for the initial-value problem are studied. Examples for k = 1, 2, and 3 were discovered by use of Adams-type methods. A large family of stiffly stable… Expand

An element of the set T= {n:τ(n) is a factor of n} is called a Tau number, where τ(n) denotes the number of divisors of the integer n. We determine the natural density of this set by use of Hardy and… Expand