题解

极限压行

#include <iostream>
using namespace std; long long arr[21]={0,1,3,9,33,153,873,5913,46233,409113,4037913,43954713,522956313,6749977113,93928268313,1401602636313,22324392524313,378011820620313,6780385526348313,128425485935180313,2561327494111820313},n; int main(){cin>>n;cout<<arr[n]<<endl;return 0;}