#include using namespace std; typedef long long ll; typedef pair p_ll; template void debug(T itr1, T itr2) { auto now = itr1; while(now=0; i--) const ll MOD = pow(10,9)+7; const ll LLINF = pow(2,61)-1; const int INF = pow(2,30)-1; vector fac; void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; } ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; } ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; } ll gcd(ll a, ll b) { if (a isp; void sieve(int x=pow(10,6)+10) { isp.resize(x,true); isp[0] = false; isp[1] = false; for (int i=2; pow(i,2)<=x; i++) { if (isp[i]) for(int j=2; i*j<=x; j++) isp[i*j] = false; } } // ---------------------------------------------------------------------- // ---------------------------------------------------------------------- int main() { ll N; cin >> N; sieve(); vector pn; rep(i,N+1) if (isp[i]) pn.push_back(i); vector p3n; rep(i,3*N+1) if (isp[i]) p3n.push_back(i); // debug(all(p3n)); ll sum[3*N+1] = {}; ll result = 0, prev = 0; for (auto x: pn) { for (auto y: pn) { if (y>=prev) break; sum[prev+y]++; } for (auto y: p3n) if (y-x>=0) result += sum[y-x]; prev = x; // debug(sum, sum+(3*N+1)); } cout << result << endl; return 0; }