Partial sums of A005578.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =13a(5) =24a(6) =46a(7) =89a(8) =175a(9) =346a(10) =688a(11) =1371a(12) =2737a(13) =5468a(14) =10930a(15) =21853a(16) =43699a(17) =87390a(18) =174772a(19) =349535a(20) =699061a(21) =1398112a(22) =2796214a(23) =5592417a(24) =11184823a(25) =22369634a(26) =44739256a(27) =89478499a(28) =178956985a(29) =357913956