Maximal period of an n-stage shift register.

Terms

a(0) =2a(1) =6a(2) =12a(3) =30a(4) =60a(5) =120a(6) =210a(7) =420a(8) =840a(9) =1260a(10) =2520a(11) =2520a(12) =5040a(13) =9240a(14) =13860a(15) =27720a(16) =32760a(17) =55440a(18) =65520a(19) =120120a(20) =180180a(21) =360360a(22) =360360a(23) =720720a(24) =720720a(25) =942480a(26) =1113840