Number of compositions of n with all adjacent parts (x,y) satisfying x < 2y and y < 2x.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =3a(5) =4a(6) =4a(7) =7a(8) =9a(9) =11a(10) =17a(11) =23a(12) =32a(13) =44a(14) =63a(15) =91a(16) =127a(17) =180a(18) =255a(19) =363a(20) =516a(21) =732a(22) =1044a(23) =1485a(24) =2109a(25) =3002a(26) =4277a(27) =6089a(28) =8660a(29) =12323