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Sum of series:
1/n^3
1/((3n-2)*(3n+1))
1/(4n^2-9)
n*3^n+1
Identical expressions
n* three ^n+ one
n multiply by 3 to the power of n plus 1
n multiply by three to the power of n plus one
n*3n+1
n3^n+1
n3n+1
Similar expressions
n*3^n-1

Sum of series/ n*3^n+1

Sum of series n*3^n+1

The solution

You have entered [src]

  oo            
 ___            
 \  `           
  \   /   n    \
  /   \n*3  + 1/
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n = 1

$$\sum_{n=1}^{\infty} \left(3^{n} n + 1\right)$$

Sum(n*3^n + 1, (n, 1, oo))

The radius of convergence of the power series

Given number:
$$3^{n} n + 1$$
It is a series of species
$$a_{n} \left(c x - x_{0}\right)^{d n}$$
- power series.
The radius of convergence of a power series can be calculated by the formula:
$$R^{d} = \frac{x_{0} + \lim_{n \to \infty} \left|{\frac{a_{n}}{a_{n + 1}}}\right|}{c}$$
In this case
$$a_{n} = 3^{n} n + 1$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{n \to \infty}\left(\frac{3^{n} n + 1}{3^{n + 1} \left(n + 1\right) + 1}\right)$$
Let's take the limit
we find

False

False

False

The rate of convergence of the power series

The answer [src]

oo

$$\infty$$

oo

Numerical answer

The series diverges

The graph

Examples of finding the sum of a series

The Sum of the Power Series
```
x^n/n
```
```
(x-1)^n
```
Factorial
```
1/2^(n!)
```
```
n^2/n!
```
```
x^n/n!
```
```
k!/(n!*(n+k)!)
```
Flint Hills Series
```
csc(n)^2/n^3
```
Basel problem
```
1/n^2
```
```
1/n^4
```
```
1/n^6
```
Harmonic series
```
1/n
```
Grandi's series
```
(-1)^n
```
Alternating series
```
(-1)^(n + 1)/n
```
```
(n + 2)*(-1)^(n - 1)
```
```
(3*n - 1)/(-5)^n
```
```
(-1)^(n - 1)*n/(6*n - 5)
```
Newton–Mercator series
```
(-1)^(n + 1)/n*x^n
```
Exam the series for convergence
```
(3*n - 1)/(-5)^n
```

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Identical expressions

Similar expressions

Sum of series n*3^n+1

The solution

Examples of finding the sum of a series