Odd integers concatenated with themselves.

Terms

a(0) =11a(1) =33a(2) =55a(3) =77a(4) =99a(5) =1111a(6) =1313a(7) =1515a(8) =1717a(9) =1919a(10) =2121a(11) =2323a(12) =2525a(13) =2727a(14) =2929a(15) =3131a(16) =3333a(17) =3535a(18) =3737a(19) =3939a(20) =4141a(21) =4343a(22) =4545a(23) =4747a(24) =4949a(25) =5151a(26) =5353a(27) =5555a(28) =5757a(29) =5959