# C++ Exercises: Print the first 20 numbers of the Pell series

## C++ Numbers: Exercise-39 with Solution

Write a C++ program to print the first 20 numbers of the Pell series.

**Sample Solution**:

**C++ Code :**

```
#include <iostream> // Including the input-output stream library
using namespace std; // Using the standard namespace
int main() // Main function
{
int n, a = 1, b = 0, c; // Declare integer variables: n for iteration, a and b for Pell series calculation, c for storing the current value
cout << "\n\n Find the first 20 numbers of the Pell series: \n"; // Display purpose
cout << " --------------------------------------------------\n"; // Display purpose
cout << " The first 20 numbers of Pell series are: "<<endl; // Display purpose
c = 0; // Initializing the first value of Pell series
cout << " " << c << " "; // Displaying the first value of Pell series
for (n = 1; n < 20; n++) // Loop to generate the Pell series
{
c = a + 2 * b; // Calculate the Pell series value
cout << c << " "; // Display the current Pell series value
a = b; // Update 'a' with the previous value of 'b'
b = c; // Update 'b' with the current value of Pell series
}
cout << endl; // Output newline for better readability
}
```

Sample Output:

Find the first 20 numbers of the Pell series: -------------------------------------------------- The first 20 numbers of Pell series are: 0 1 2 5 12 29 70 169 408 985 2378 5741 13860 33461 80782 195025 470832 1136689 2744210 6625109

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