Partial sums of A081660.

Terms

a(0) =1a(1) =3a(2) =8a(3) =16a(4) =31a(5) =57a(6) =106a(7) =198a(8) =377a(9) =727a(10) =1420a(11) =2796a(12) =5539a(13) =11013a(14) =21950a(15) =43810a(16) =87517a(17) =174915a(18) =349696a(19) =699240a(20) =1398311a(21) =2796433a(22) =5592658a(23) =11185086a(24) =22369921a(25) =44739567a(26) =89478836a(27) =178957348a(28) =357914347a(29) =715828317