Concatenation of sequences (1,3,..,2n-1,2n,2n-2,..,2) for n >= 1.

Terms

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