Number of integer compositions of n containing two adjacent ones and no other runs.

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =2a(5) =4a(6) =5a(7) =14a(8) =26a(9) =46a(10) =92a(11) =176a(12) =323a(13) =610a(14) =1145a(15) =2108a(16) =3912a(17) =7240a(18) =13289a(19) =24418a(20) =44778a(21) =81814a(22) =149356a(23) =272222a(24) =495144a(25) =899554a(26) =1632176a(27) =2957332a(28) =5352495a(29) =9677266