Number of compositions of n where neighboring runs have different lengths.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =5a(5) =8a(6) =13a(7) =24a(8) =42a(9) =68a(10) =122a(11) =210a(12) =360a(13) =622a(14) =1077a(15) =1858a(16) =3198a(17) =5519a(18) =9549a(19) =16460a(20) =28386a(21) =49031a(22) =84595a(23) =145988a(24) =251956a(25) =434805a(26) =750418a(27) =1294998a(28) =2234971a(29) =3857106