Smallest member of sociable quadruples using Dedekind psi function (A001615).

Terms

a(0) =11398670a(1) =22797340a(2) =38369450a(3) =45594680a(4) =56993350a(5) =59334310a(6) =76738900a(7) =91189360a(8) =113986700a(9) =118668620a(10) =153477800a(11) =182378720a(12) =209524210a(13) =227973400a(14) =237337240a(15) =268586150a(16) =284966750a(17) =306955600a(18) =364757440a(19) =419048420a(20) =455946800a(21) =474674480a(22) =537172300a(23) =539867650a(24) =569933500