#include <stdio.h> int main(){ int a[50]; int i; int n; a[0]=0,a[1]=3,a[2]=6,a[3]=6; for(i=4;i<=50;i++) a[i]=2*a[i-2]+a[i-1]; while (scanf("%d",&n)!=EOF){ printf("%d\n",a[n]); } return 0; }
Double click to view unformatted code.