Number of compositions of n with all adjacent parts (x, y) satisfying x >= 2y or y > 2x.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =4a(6) =6a(7) =11a(8) =16a(9) =23a(10) =35a(11) =54a(12) =82a(13) =125a(14) =193a(15) =294a(16) =447a(17) =680a(18) =1037a(19) =1580a(20) =2408a(21) =3676a(22) =5606a(23) =8544a(24) =13024a(25) =19860a(26) =30277a(27) =46155a(28) =70374a(29) =107300