Number of compositions of n with either all parts odd or all parts even.

Terms

a(0) =1a(1) =2a(2) =2a(3) =5a(4) =5a(5) =12a(6) =13a(7) =29a(8) =34a(9) =71a(10) =89a(11) =176a(12) =233a(13) =441a(14) =610a(15) =1115a(16) =1597a(17) =2840a(18) =4181a(19) =7277a(20) =10946a(21) =18735a(22) =28657a(23) =48416a(24) =75025a(25) =125489a(26) =196418a(27) =326003a(28) =514229a(29) =848424