A bisection of A188624.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =19a(5) =56a(6) =180a(7) =596a(8) =2015a(9) =6904a(10) =23923a(11) =83755a(12) =296084a(13) =1056095a(14) =3797790a(15) =13757665a(16) =50164787a(17) =183980036a(18) =678215028a(19) =2511483176a(20) =9337575130a(21) =34840575458a(22) =130412367572a(23) =489546890178