#include <cstdio>
#include <cstring>
#include <string>
#include <iostream>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;
const ll MOD=1e9+7;
int main()
{
	int n, k;
  cin>>n>>k;
  ll dp[301][45001]={}, s[301][45001];
  for(int i=1; i<=n; i++){
    dp[i][0]=1;
    s[i][0]=1;
  }
  for(int i=1; i<n; i++){
      for(int l=1; l<=i*(i+1)/2; l++){
        if(l-i-1>=0) dp[i+1][l]+=(s[i][min(i*(i-1)/2, l)]+MOD-s[i][l-i-1]);
        else dp[i+1][l]+=s[i][min(i*(i-1)/2, l)];
        dp[i+1][l]%=MOD;
        s[i+1][l]=(s[i+1][l-1]+dp[i+1][l])%MOD;
      }
  }
  ll ans=0;
  for(int i=0; i<=k; i++){
    ans+=dp[n][i];
    ans%=MOD;
  }
  cout<<ans<<endl;
	return 0;
}