Number of compositions of n that are either strictly increasing or strictly decreasing.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =3a(5) =5a(6) =7a(7) =9a(8) =11a(9) =15a(10) =19a(11) =23a(12) =29a(13) =35a(14) =43a(15) =53a(16) =63a(17) =75a(18) =91a(19) =107a(20) =127a(21) =151a(22) =177a(23) =207a(24) =243a(25) =283a(26) =329a(27) =383a(28) =443a(29) =511