Partial sums of floor(2^n/9).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =4a(6) =11a(7) =25a(8) =53a(9) =109a(10) =222a(11) =449a(12) =904a(13) =1814a(14) =3634a(15) =7274a(16) =14555a(17) =29118a(18) =58245a(19) =116499a(20) =233007a(21) =466023a(22) =932056a(23) =1864123a(24) =3728258a(25) =7456528a(26) =14913068a(27) =29826148a(28) =59652309a(29) =119304632