Number of compositions of n whose circular differences are all 1 or -1.

Terms

a(0) =0a(1) =0a(2) =2a(3) =0a(4) =2a(5) =2a(6) =2a(7) =4a(8) =4a(9) =2a(10) =8a(11) =6a(12) =8a(13) =10a(14) =12a(15) =16a(16) =18a(17) =20a(18) =28a(19) =34a(20) =42a(21) =48a(22) =62a(23) =78a(24) =92a(25) =112a(26) =146a(27) =174a(28) =216a(29) =264