a(n) = A080069(n) OR A267357(n).

Terms

a(0) =1a(1) =3a(2) =15a(3) =47a(4) =191a(5) =743a(6) =2935a(7) =12015a(8) =47615a(9) =190363a(10) =737255a(11) =3092431a(12) =11777535a(13) =48562151a(14) =194672615a(15) =778681963a(16) =3117668351a(17) =12677730147a(18) =49850341191a(19) =192901085003a(20) =795560607711