Number of reversible strings with n black beads and n-1 white beads. String is not palindromic.

A032106

Number of reversible strings with n black beads and n-1 white beads. String is not palindromic.

Terms

    a(0) =1a(1) =1a(2) =4a(3) =16a(4) =60a(5) =226a(6) =848a(7) =3200a(8) =12120a(9) =46126a(10) =176232a(11) =675808a(12) =2599688a(13) =10028292a(14) =38777664a(15) =150266880a(16) =583395120a(17) =2268771670a(18) =8836291640a(19) =34461586016a(20) =134564376232a(21) =526024564572

External references