Number of non-alternating compositions of n.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =4a(5) =9a(6) =20a(7) =45a(8) =99a(9) =208a(10) =437a(11) =906a(12) =1862a(13) =3803a(14) =7732a(15) =15659a(16) =31629a(17) =63747a(18) =128258a(19) =257722a(20) =517339a(21) =1037652a(22) =2079984a(23) =4167325a(24) =8346204a(25) =16710572a(26) =33449695a(27) =66944254a(28) =133959021a(29) =268028868