A nonsense sequence.

Terms

a(0) =3a(1) =7a(2) =311a(3) =313a(4) =317a(5) =9733a(6) =9739a(7) =10973a(8) =10979a(9) =31097317a(10) =73109731091a(11) =97310973101a(12) =97310973103