Number of length-2n central circular binary strings without zigzags (see reference for precise definition).

A263656

Number of length-2n central circular binary strings without zigzags (see reference for precise definition).

Terms

    a(0) =0a(1) =0a(2) =4a(3) =6a(4) =12a(5) =30a(6) =70a(7) =168a(8) =412a(9) =1014a(10) =2514a(11) =6270a(12) =15702a(13) =39468a(14) =99516a(15) =251586a(16) =637500a(17) =1618638a(18) =4117102a(19) =10488684a(20) =26758762a(21) =68354250a(22) =174810354a(23) =447533586a(24) =1146836662a(25) =2941443180a(26) =7550434480a(27) =19395863358a(28) =49859516292a(29) =128252962434

External references