Bisection of A000043.

Terms

a(0) =2a(1) =5a(2) =13a(3) =19a(4) =61a(5) =107a(6) =521a(7) =1279a(8) =2281a(9) =4253a(10) =9689a(11) =11213a(12) =21701a(13) =44497a(14) =110503a(15) =216091a(16) =859433a(17) =1398269a(18) =3021377a(19) =13466917a(20) =24036583a(21) =30402457a(22) =37156667a(23) =43112609