NumberSequenceTriangle.java

public class HelloWorld{
    
        static int a= 1;
     public static void main(String []args){
        
        int n=5;
        for(int i=0;i<n;i++)
        {
            int k=i;
        for(int j=0;j<=k;j++)
        {  
         System.out.print(" "+a); 
         a=a+1;
        }
        System.out.println(""); 
        }
     }
}

//OUTPUT

 1                                                                                                                                                               
 2 3                                                                                                                                                             
 4 5 6                                                                                                                                                           
 7 8 9 10                                                                                                                                                        
 11 12 13 14 15