#include "bits/stdc++.h"

#define ALL(g) (g).begin(),(g).end()
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define RREP(i, x, n) for(int i = x; i >= n; i--)
#define rrep(i, n) RREP(i,n,0)
#define pb push_back
#define show_table(n, k, table) rep(i,n){ rep(j,k) cout << table[i][j] << " "; cout << endl;}

template<class T> void chmax(T& a,const T& b){a=max(a,b);}
template<class T> void chmin(T& a,const T& b){a=min(a,b);}

using namespace std;

using ll = long long;
using P = pair<int,int>;
using Pl = pair<ll,ll>;
using vi = vector<int>;
using vvi = vector<vi>;

const int mod=1e9+7,INF=1<<30;
const double EPS=1e-12,PI=3.1415926535897932384626;
const ll lmod = 1e9+7,LINF=1LL<<60;
const int MAX_N = 302;

ll dp[MAX_N][MAX_N*MAX_N/2],sum[MAX_N][MAX_N*MAX_N/2];

int main(){
  int N,K; cin >> N >> K;
  // int a; rep(i,N) cin >> a;
  dp[0][0] = 1;
  rep(j,K+1) sum[0][j] = 1LL;
  REP(i,1,N){
    rep(j,K+1){
      if(min(i,j)<=j-1) dp[i][j] = (sum[i-1][j] - sum[i-1][j-min(i,j)-1])%lmod;
      else dp[i][j] = sum[i-1][j];
    }
    sum[i][0] = 1LL;
    REP(j,1,K+1) sum[i][j] = (sum[i][j-1] + dp[i][j])%lmod;
  }
  // show_table(N,K+1,dp);
  cout << sum[N-1][K] << endl;
  return 0;
}