a(n) is the multiplicative order of the n-th prime number q modulo (q-1)#.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =6a(5) =20a(6) =60a(7) =120a(8) =144a(9) =7920a(10) =18480a(11) =18480a(12) =7920a(13) =27720a(14) =2520a(15) =637560a(16) =8288280a(17) =480720240a(18) =240360120a(19) =480720240a(20) =480720240a(21) =480720240a(22) =240360120a(23) =9854764920a(24) =19709529840a(25) =9854764920a(26) =16424608200a(27) =670124014560