Number of 0's in the top rows of all 2-compositions of n.

Terms

a(0) =0a(1) =1a(2) =5a(3) =23a(4) =99a(5) =408a(6) =1632a(7) =6388a(8) =24596a(9) =93488a(10) =351664a(11) =1311536a(12) =4856432a(13) =17873408a(14) =65436544a(15) =238480960a(16) =865665600a(17) =3131196672a(18) =11290210560a(19) =40594476800a(20) =145588087552a(21) =520933746688