python3 - <<'EOF' from array import array A=[2,3,4,5,7,9,11,13,16,17,19,23,25,29,31,36,37,41,43,47,49] N=21 M=1<2: u=4*(n[m]*Q[m]-S[m]*S[m]) d=n[m]*n[m] if u%d==0 and u//d in T: p,q=T[u//d] if (m>>p)&1 and (m>>q)&1: H.add((p,q)) print(sorted(H)) EOF