﻿ Java - Display first 10 lucus numbers

# Java: Display first 10 lucus numbers

## Java Numbers: Exercise-7 with Solution

Write a Java program to display the first 10 lucus numbers.

The Lucas numbers or series are an integer sequence named after the mathematician François Édouard Anatole Lucas, who studied both that sequence and the closely related Fibonacci numbers. Lucas numbers and Fibonacci numbers form complementary instances of Lucas sequences.
The sequence of Lucas numbers is: 2, 1, 3, 4, 7, 11, 18, 29, ….

Sample Solution:

Java Code:

``````import java.util.Scanner;
public class Example7 {
public static void main(String[] args) {

System.out.print("\nFirst ten Lucas a numbers: ");
int n = 10;
int n1 = 2, n2 = 1, n3;
if (n > 1){
System.out.println("\n2\n1");
for(int i = 2; i < n; ++i){
n3 = n2;
n2 += n1;
n1 = n3;
System.out.println(n2);
}
}
else if (n == 1)
System.out.println("\n2");

else
System.out.println("Input a positive number.");
}
}
```
```

Sample Output:

```First ten Lucas a numbers:
2
1
3
4
7
11
18
29
47
76
```

Flowchart: Java Code Editor:

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## Java: Tips of the Day

IsPowerOfTwo

Checks if a value is positive power of two.

To understand how it works let's assume we made a call IsPowerOfTwo(4).

As value is greater than 0, so right side of the && operator will be evaluated.

The result of (~value + 1) is equal to value itself. ~100 + 001 => 011 + 001 => 100. This is equal to value.

The result of (value & value) is value. 100 & 100 => 100.

This will value the expression to true as value is equal to value.

```public static boolean isPowerOfTwo(final int value) {
return value > 0 && ((value & (~value + 1)) == value);
}
```

Ref: https://bit.ly/3sA5d4I

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