Bisection of A007059.

Terms

a(0) =0a(1) =1a(2) =3a(3) =8a(4) =24a(5) =77a(6) =256a(7) =874a(8) =3045a(9) =10780a(10) =38674a(11) =140268a(12) =513350a(13) =1892875a(14) =7023562a(15) =26200182a(16) =98182666a(17) =369393466a(18) =1394632365a(19) =5281753216a(20) =20058841004a(21) =76370762838a(22) =291436246116