题解（打表）

#include <stdio.h>
int main()
{
    int n;
    scanf("%d",&n);
    int a[30] = {1,2,4,7,12,21,37,65,114,200,351,616,1081,1897,3329,5842,10252,17991,31572,55405,97229,170625,299426,525426,922111,1618192,2839729,4983377,8745217,15346786};
    printf("%d",a[n-1]);
    return 0;
}