Unitary sociable numbers of order 4.

Terms

a(0) =263820a(1) =263940a(2) =280380a(3) =280500a(4) =395730a(5) =395910a(6) =420570a(7) =420750a(8) =172459210a(9) =209524210a(10) =218628662a(11) =218725430a(12) =230143790a(13) =231439570a(14) =246667790a(15) =272130250a(16) =384121920a(17) =384296640a(18) =408233280a(19) =408408000