Number of (0, 1)-necklaces of length n without zigzags (see reference for precise definition).

Terms

a(0) =0a(1) =2a(2) =2a(3) =2a(4) =3a(5) =4a(6) =5a(7) =6a(8) =8a(9) =10a(10) =15a(11) =20a(12) =31a(13) =42a(14) =64a(15) =94a(16) =143a(17) =212a(18) =329a(19) =494a(20) =766a(21) =1170a(22) =1811a(23) =2788a(24) =4341a(25) =6714a(26) =10462a(27) =16274a(28) =25415a(29) =39652