Convolution of A270913 and A008485.

Terms

a(0) =1a(1) =2a(2) =9a(3) =43a(4) =206a(5) =999a(6) =4915a(7) =24372a(8) =121698a(9) =611244a(10) =3085612a(11) =15645347a(12) =79639602a(13) =406809249a(14) =2084567381a(15) =10712007629a(16) =55187254157a(17) =284981396231