How to write series program in java

 1/a² + 1/a³ + 1/a⁴-----n

// always focus on first term  then see the difference in first and second term

Normal way

double a=3.0, b=2.0,sum=0.0;  // "a " value you can take anything

int n=10  // n value you can take any thing

for(int i=1;i<=n;i++)

{

sum=sum+ 1/ Math.pow(a,b);

b++;

}

System.out.println(sum);

Short cut way

double sum=0.0,a=3.0;  // "a" value you can take anything

int n=10  // n value you can take any thing

for(int i=1;i<=n;i++)

{

sum=sum+ 1/ Math.pow(a, (i+1));

}

System.out.println(sum);