Iteration of unitary-sigma function: a(1) = 2, a(n) = usigma(a(n-1)).

Terms

a(0) =2a(1) =3a(2) =4a(3) =5a(4) =6a(5) =12a(6) =20a(7) =30a(8) =72a(9) =90a(10) =180a(11) =300a(12) =520a(13) =756a(14) =1120a(15) =1584a(16) =2040a(17) =3888a(18) =4148a(19) =5580a(20) =9600a(21) =13416a(22) =22176a(23) =31680a(24) =46800a(25) =61880a(26) =108864a(27) =126880a(28) =171864a(29) =276480