Partial sums of A000602.

Terms

a(0) =1a(1) =2a(2) =3a(3) =4a(4) =6a(5) =9a(6) =14a(7) =23a(8) =41a(9) =76a(10) =151a(11) =310a(12) =665a(13) =1467a(14) =3325a(15) =7672a(16) =18031a(17) =42925a(18) =103448a(19) =251732a(20) =618051a(21) =1528777a(22) =3807435a(23) =9539015a(24) =24029260a(25) =60826848a(26) =154666260a(27) =394882063a(28) =1011987677a(29) =2602494798