A hierarchical sequence (S(W2{3}*) - see A059126).

Terms

a(0) =11a(1) =40a(2) =105a(3) =242a(4) =523a(5) =1092a(6) =2237a(7) =4534a(8) =9135a(9) =18344a(10) =36769a(11) =73626a(12) =147347a(13) =294796a(14) =589701a(15) =1179518a(16) =2359159a(17) =4718448a(18) =9437033a(19) =18874210a(20) =37748571a(21) =75497300a(22) =150994765a(23) =301989702a(24) =603979583a(25) =1207959352a(26) =2415918897a(27) =4831837994a(28) =9663676195a(29) =19327352604