a(n) = Sum_{k=0..n} A026615(n, k).

Terms

a(0) =1a(1) =2a(2) =5a(3) =12a(4) =26a(5) =54a(6) =110a(7) =222a(8) =446a(9) =894a(10) =1790a(11) =3582a(12) =7166a(13) =14334a(14) =28670a(15) =57342a(16) =114686a(17) =229374a(18) =458750a(19) =917502a(20) =1835006a(21) =3670014a(22) =7340030a(23) =14680062a(24) =29360126a(25) =58720254a(26) =117440510a(27) =234881022a(28) =469762046a(29) =939524094