plz find how this code can give an exact answer

Question

find nth term of series 1 1 2 3 4 9 8 27 16 81 32........
n cant exceed 30;
alternate terms consists of g.p

#include<stdio.h>
#include<math.h>
void two(int a);
void three(int b);
int main(int argc,char *argv[])
{
    int n;
n=atoi(argv[1]);
    scanf("%d",&n);
        if(n<=0)
    {
        printf("invalid term");
    }
    if(n%2==0)
    {
      if (n==2)
{
      printf("1");
}   
        three(n);
    }
   
        if(n%2!=0)
    {
        if (n==1)
{
      printf("1");
}   
        two(n);
    }
   
}
void two(int a)
{
    printf("%d",pow(2,(a/2)));
   
}

void three(int b)
{
    printf("%d",pow(3,(b/2)));
   
}

Answer 1

#include<iostream.h>

void main()

{

int a[30],i;

char c;

a[0]=1;

a[1]=1;

for(i=1;i<=15;i++)

a[2*i]=2*a[2*i-2];

for(i=0;i<=15;i++)

a[2*i+1]=3*a[2*i-1];

while(c!='n')

{

cout<<"enter n";

cin>>n;

cout<<a[n-1];

cout<<"do you want another number?";

cin>>n;

}

}