Number of up/down (initially ascending) compositions of n.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =7a(7) =11a(8) =16a(9) =26a(10) =41a(11) =64a(12) =100a(13) =158a(14) =247a(15) =389a(16) =612a(17) =960a(18) =1509a(19) =2372a(20) =3727a(21) =5858a(22) =9207a(23) =14468a(24) =22738a(25) =35737a(26) =56164a(27) =88268a(28) =138726a(29) =218024