#include<bits/stdc++.h>
using namespace std;
#define all(fl) fl.begin(),fl.end()
#define pb push_back
#define fi first
#define se second
#define for1(i,j,k) for(int i=j;i<=k;i++)
#define for2(i,j,k) for(int i=j;i>=k;i--)
#define for3(i,j,k,l) for(int i=j;i<=k;i+=l)
#define lb lower_bound
#define ub upper_bound
#define sz(a) (int)a.size()
#define pii pair<int,int>
#define pli pair<long long,int>
#define gcd __gcd
#define lcm(x,y) x*y/__gcd(x,y)
#define pil pair<int,long long>
#define pll pair<long long,long long>
#define eb emplace_back
const long long du=1e9+7;
long long f[301][301][301];
long long combi[3001][3001];
long long pw[3001];
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("temp.INP","r",stdin);
//freopen("temp.OUT","w",stdout);
int m,n;
cin>>m>>n;
pw[0]=1;
for1(i,1,3000)pw[i]=(pw[i-1]*4)%du;
combi[0][0]=1;
for1(i,1,3000){
combi[i][0]=1;
for1(j,1,3000){
combi[i][j]=(combi[i-1][j-1]+combi[i-1][j])%du;
}
}
f[0][0][0]=1;
for1(i,1,m){
for1(j,0,n){
for1(k,0,n){
if (j+k>n)break;
//j take 1 k take 2
int can=n-j-k;
f[i][j][k]=(f[i][j][k]+f[i-1][j][k])%du;
if (j+1+k<=n){
f[i][j+1][k]=(f[i][j+1][k]+f[i-1][j][k]*can)%du;
}
if (j-1>=0){
f[i][j-1][k+1]=(f[i][j-1][k+1]+f[i-1][j][k]*j)%du;
}
if (j+k+2<=n){
f[i][j][k+2]=(f[i][j][k+2]+f[i-1][j][k]*combi[can][2])%du;
}
}
}
}
long long ans=0;
for1(j,0,n){
for1(k,0,n){
ans=(ans+f[m][j][k]*pw[j])%du;
}
}
cout<<(ans-1+du)%du;
}
