Does the sum of all series 1/n^m, m>1 converge?

This is a geometric series with a common ratio of 1/n, which converges to 1/(1-1/n) = n/(n-1). Now, the outer sum is just adding up these terms for different values of n, so in summary, ##\sum_{m=2}^\infty \sum_{n=2}^\infty 1/n^m ## converges to the sum of all these individual terms, which is equal to ##\sum_{n=2}^\infty n/(n-1)##. This series also converges, as the terms approach 1 as n approaches infinity.
  • #1
BWV
1,465
1,781
##\sum_{n=1}^\infty 1/n^2 ## converges to ##π^2/6##

and every other series with n to a power greater than 1 for n∈ℕ convergesis it known if the sum of all these series - ##\sum_{m=2}^\infty \sum_{n=1}^\infty 1/n^m ## for n∈ℕ converges?

apologies for any notational flaws
 
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  • #2
Duh, so as every sum is >1 they of course the double sum above would diverge, but is there anything interesting about the partial sums or

##\sum_{m=2}^\infty \sum_{n=2}^\infty 1/n^m ## ?
 
  • #3
A more interesting question is what is the result when the n sum starts at n=2.
 
  • #4
mathman said:
A more interesting question is what is the result when the n sum starts at n=2.

Looks like it converges to 1

ran n to 2:1000 then 2:10000 in Matlab, n(1000)=0.9990, n(10,000)=0.9999
 
  • #5
BWV said:
Duh, so as every sum is >1 they of course the double sum above would diverge, but is there anything interesting about the partial sums or

##\sum_{m=2}^\infty \sum_{n=2}^\infty 1/n^m ## ?
Flip the sums and focus on the ##\sum_{m=2}^\infty 1/n^m## part first.
 

1. What is the definition of convergence for a series?

The sum of a series is said to converge if the limit of the partial sums exists and is finite. In other words, if the sum of all the terms in the series approaches a finite value as more terms are added, then the series is said to converge.

2. How can I determine if a series converges or diverges?

There are several tests that can be used to determine the convergence or divergence of a series, such as the comparison test, ratio test, and integral test. These tests involve comparing the given series to a known convergent or divergent series or using calculus to evaluate the behavior of the series.

3. What is the significance of the value of m in the series 1/n^m?

The value of m in the series 1/n^m represents the power to which the denominator is raised. This power can affect the behavior of the series and determine whether it converges or diverges. For example, if m is greater than 1, the series is more likely to converge, while if m is less than or equal to 1, the series is more likely to diverge.

4. Can the sum of all series 1/n^m converge for all values of m?

No, the sum of all series 1/n^m cannot converge for all values of m. It is possible for the series to converge for some values of m and diverge for others. The behavior of the series is highly dependent on the value of m and cannot be generalized for all values.

5. How does the convergence of the series 1/n^m relate to the convergence of other series?

The convergence of the series 1/n^m is related to the convergence of other series through various tests, such as the comparison test and the ratio test. By comparing the given series to known convergent or divergent series, we can determine the convergence of the series 1/n^m and make conclusions about its behavior.

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