The poor sandwiches sequence (see Comments lines for definition).

Terms

a(0) =2a(1) =1a(2) =110a(3) =10a(4) =1101a(5) =11010a(6) =3a(7) =330a(8) =30a(9) =3303a(10) =33030a(11) =4a(12) =440a(13) =40a(14) =4404a(15) =44040a(16) =5a(17) =550a(18) =50a(19) =5505a(20) =55050a(21) =6a(22) =660a(23) =60a(24) =6606a(25) =66060a(26) =7a(27) =770a(28) =70a(29) =7707