Replace 2n+1 with concatenation of its divisors >1.

Terms

a(0) =0a(1) =3a(2) =5a(3) =7a(4) =39a(5) =11a(6) =13a(7) =3515a(8) =17a(9) =19a(10) =3721a(11) =23a(12) =525a(13) =3927a(14) =29a(15) =31a(16) =31133a(17) =5735a(18) =37a(19) =31339a(20) =41a(21) =43a(22) =3591545a(23) =47a(24) =749a(25) =31751a(26) =53a(27) =51155a(28) =31957a(29) =59