Length of shortest addition chain for n.

Terms

a(0) =0a(1) =1a(2) =2a(3) =2a(4) =3a(5) =3a(6) =4a(7) =3a(8) =4a(9) =4a(10) =5a(11) =4a(12) =5a(13) =5a(14) =5a(15) =4a(16) =5a(17) =5a(18) =6a(19) =5a(20) =6a(21) =6a(22) =6a(23) =5a(24) =6a(25) =6a(26) =6a(27) =6a(28) =7a(29) =6