Math Problem Statement

Let n be an integer such that 1241 ≤ n and gcd(n, ⌊√n!⌋) = 1. What is the smallest possible value of n satisfying the conditions above?

Solution

We are given an integer nn such that 1241n1241 \leq n and gcd(n,n!)=1\gcd(n, \lfloor \sqrt{n!} \rfloor) = 1. The goal is to find the smallest possible value of nn that satisfies these conditions.

Step-by-Step Solution:

  1. Understanding the problem:

    • gcd(n,n!)=1\gcd(n, \lfloor \sqrt{n!} \rfloor) = 1 means that nn and n!\lfloor \sqrt{n!} \rfloor must be coprime, i.e., they should not share any common factors.
    • n!n! is the factorial of nn, and n!\lfloor \sqrt{n!} \rfloor is the greatest integer less than or equal to the square root of n!n!.
  2. Exploration of n!n!:

    • The factorial n!n! grows very quickly with increasing nn, and its square root n!\sqrt{n!} is also large. We need to find the smallest n1241n \geq 1241 such that nn is coprime with n!\lfloor \sqrt{n!} \rfloor.
  3. Testing small values of n1241n \geq 1241:

    • We begin by checking if the values of gcd(n,n!)\gcd(n, \lfloor \sqrt{n!} \rfloor) are equal to 1 for small values of nn starting at 1241.

This process involves calculating the factorials, their square roots, and checking for coprimeness for values of nn. I will calculate this to find the smallest nn.The smallest value of nn that satisfies the conditions 1241n1241 \leq n and gcd(n,n!)=1\gcd(n, \lfloor \sqrt{n!} \rfloor) = 1 is n=1241n = 1241. For this value of nn:

  • 1241!\lfloor \sqrt{1241!} \rfloor is a very large number, but it shares no common factors with n=1241n = 1241, hence the greatest common divisor (GCD) is 1.

Would you like to explore further details or have any questions?

Here are some follow-up questions:

  1. How is the factorial function defined for large numbers?
  2. What methods can be used to approximate large factorials like 1241!1241!?
  3. Why does the GCD condition guarantee that nn and n!\lfloor \sqrt{n!} \rfloor are coprime?
  4. How does the square root of factorial grow as nn increases?
  5. Can this method be applied for different starting values of nn?

Tip: When working with large factorials, techniques like Stirling's approximation can be useful for approximating the values efficiently.

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Math Problem Analysis

Mathematical Concepts

Factorials
Greatest Common Divisor (GCD)
Number Theory

Formulas

Factorial: n! = n × (n-1) × (n-2) × ... × 1
Greatest Common Divisor: gcd(a, b)
Square Root Approximation: ⌊√n!⌋

Theorems

Properties of GCD
Factorial Growth

Suitable Grade Level

Grades 10-12