a(n)=(# 1's)-(# 2's) in first n terms of A003137.

Terms

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