Number of compositions of n avoiding the pattern 1111.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =7a(5) =15a(6) =26a(7) =52a(8) =93a(9) =173a(10) =310a(11) =556a(12) =1041a(13) =1789a(14) =3098a(15) =5620a(16) =9725a(17) =16377a(18) =28764a(19) =48518a(20) =82889a(21) =137161a(22) =237502a(23) =390084a(24) =646347a(25) =1055975a(26) =1774036a(27) =2907822a(28) =4698733a(29) =7581093