c++ -x c++ -O2 -o /tmp/a - <<'EOF'
#include <bits/stdc++.h>
using namespace std;
int main(){
vector<int>A={2,3,4,5,7,9,11,13,16,17,19,23,25,29,31,36,37,41,43,47,49};
int N=21,M=1<<N;
unordered_map<long long,vector<pair<int,int>>>T;
for(int i=0;i<N;i++)for(int j=i+1;j<N;j++){auto d=A[j]-A[i];T[1LL*d*d].push_back({i,j});}
vector<unsigned char>n(M);vector<int>S(M),Q(M);
for(int m=1;m<M;m++){int l=m&-m,b=__builtin_ctz(l),p=m^l;n[m]=n[p]+1;S[m]=S[p]+A[b];Q[m]=Q[p]+A[b]*A[b];}
set<pair<int,int>>R;
for(int m=1;m<M;m++)if(n[m]>2){long long u=4LL*(1LL*n[m]*Q[m]-1LL*S[m]*S[m]),d=1LL*n[m]*n[m];if(u%d==0){auto it=T.find(u/d);if(it!=T.end())for(auto [i,j]:it->second)if((m>>i& 1)&&(m>>j& 1))R.insert({i,j});}}
for(auto [i,j]:R)cout<<A[i]<<','<<A[j]<<';';cout<<'\n';}
EOF
/tmp/a