Number of integer compositions of n whose parts are not in arithmetic progression.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =3a(5) =10a(6) =22a(7) =56a(8) =118a(9) =241a(10) =498a(11) =1012a(12) =2026a(13) =4082a(14) =8174a(15) =16356a(16) =32747a(17) =65518a(18) =131038a(19) =262124a(20) =524260a(21) =1048538a(22) =2097124a(23) =4194280a(24) =8388562a(25) =16777185a(26) =33554400a(27) =67108816a(28) =134217690a(29) =268435426