View Code of Problem 73

#include <stdio.h>
int main(){
	int n,i;
	scanf("%d",&n);
	int a[n];
	a[0]=1;
	for(i=0;i<=n-2;i++){
		a[i+1]=(a[i]+1)*2; 
		
	}
	printf("%d",a[n-1]);
	return 0;
}