How to resolve the algorithm Numbers which are the cube roots of the product of their proper divisors step by step in the C# programming language
How to resolve the algorithm Numbers which are the cube roots of the product of their proper divisors step by step in the C# programming language
Table of Contents
Problem Statement
Consider the number 24. Its proper divisors are: 1, 2, 3, 4, 6, 8 and 12. Their product is 13,824 and the cube root of this is 24. So 24 satisfies the definition in the task title. Compute and show here the first 50 positive integers which are the cube roots of the product of their proper divisors. Also show the 500th and 5,000th such numbers. Compute and show the 50,000th such number. OEIS considers 1 to be the first number in this sequence even though, strictly speaking, it has no proper divisors. Please therefore do likewise.
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Numbers which are the cube roots of the product of their proper divisors step by step in the C# programming language
The provided C# code determines whether a given positive integer n
has exactly four or eight distinct positive divisors, including 1 and n
itself. If n
satisfies this condition, it then checks if n
is the cube root of the product of all its proper divisors (divisors excluding n
). The program continues this process until it finds the first 50 such numbers and prints them.
Here's a detailed explanation of the code:
- The
dc8
function takes an unsigned 32-bit integern
as an argument. It calculates the number of distinct positive divisors ofn
by grouping together consecutive powers of 2, 3, and other prime factors. It returnstrue
ifn
has exactly four or eight distinct positive divisors, andfalse
otherwise. - The
Main
method initializes variables for counting, limiting, and printing. It then enters a loop that iterates through positive integersn
starting from 1. - For each
n
, it checks ifn
is equal to 1 or if it has exactly four or eight distinct positive divisors by calling thedc8
function. If either condition is met, it increments thecount
and printsn
in a formatted way. - The loop continues until it finds the first 50 numbers that meet the specified conditions, or reaches the limit
lmt
. Every time thecount
reacheslmt
, the limit is multiplied by 10 to increase the search range. - The program prints the first 50 numbers that satisfy the given conditions in a tabular format, with 10 numbers per line.
In summary, the code efficiently checks if a given number n
has exactly four or eight distinct positive divisors and then determines if n
is the cube root of the product of its proper divisors. It outputs the first 50 such numbers, providing insights into the properties of positive integers and their divisors.
Source code in the csharp programming language
using System;
class Program {
static bool dc8(uint n) {
uint res = 1, count, p, d;
for ( ; (n & 1) == 0; n >>= 1) res++;
for (count = 1; n % 3 == 0; n /= 3) count++;
for (p = 5, d = 4; p * p <= n; p += d = 6 - d)
for (res *= count, count = 1; n % p == 0; n /= p) count++;
return n > 1 ? res * count == 4 : res * count == 8;
}
static void Main(string[] args) {
Console.WriteLine("First 50 numbers which are the cube roots of the products of "
+ "their proper divisors:");
for (uint n = 1, count = 0, lmt = 500; count < 5e6; ++n) if (n == 1 || dc8(n))
if (++count <= 50) Console.Write("{0,3}{1}",n, count % 10 == 0 ? '\n' : ' ');
else if (count == lmt) Console.Write("{0,16:n0}th: {1:n0}\n", count, n, lmt *= 10);
}
}
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