Number of 3-unbalanced strings of length n (= 2^n - A027557(n)).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =2a(5) =6a(6) =20a(7) =50a(8) =126a(9) =288a(10) =654a(11) =1422a(12) =3068a(13) =6474a(14) =13574a(15) =28112a(16) =57942a(17) =118566a(18) =241788a(19) =490914a(20) =994334a(21) =2008512a(22) =4050398a(23) =8154014a(24) =16396668a(25) =32935194a(26) =66104982a(27) =132586416a(28) =265792070a(29) =532579830