Number of compositions of n that are neither weakly increasing nor weakly decreasing.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =4a(6) =14a(7) =36a(8) =88a(9) =199a(10) =432a(11) =914a(12) =1900a(13) =3896a(14) =7926a(15) =16036a(16) =32311a(17) =64944a(18) =130308a(19) =261166a(20) =523040a(21) =1046996a(22) =2095152a(23) =4191796a(24) =8385466a(25) =16773303a(26) =33549564a(27) =67102848a(28) =134210298a(29) =268426328