384121920domain: NAppears in sequencesUnitary-sociable numbers (smallest member of each cycle).at n=15A000173Irregular triangle with 4 columns which contains in each row the members of a 4-cycle under the map x->A063919(x), iteration of summing the proper-unitary divisors.at n=16A098188Unitary sociable numbers of order 4.at n=16A319902