Number of compositions of n with at least 1 odd and 1 even part.

Terms

a(0) =0a(1) =0a(2) =2a(3) =3a(4) =11a(5) =20a(6) =51a(7) =99a(8) =222a(9) =441a(10) =935a(11) =1872a(12) =3863a(13) =7751a(14) =15774a(15) =31653a(16) =63939a(17) =128232a(18) =257963a(19) =517011a(20) =1037630a(21) =2078417a(22) =4165647a(23) =8340192a(24) =16702191a(25) =33428943a(26) =66912446a(27) =133891725a(28) =267921227a(29) =536022488