Partial sums of A003214.

Terms

a(0) =1a(1) =2a(2) =4a(3) =7a(4) =13a(5) =23a(6) =43a(7) =80a(8) =156a(9) =308a(10) =628a(11) =1300a(12) =2754a(13) =5908a(14) =12867a(15) =28306a(16) =62914a(17) =140902a(18) =317887a(19) =721397a(20) =1646080a(21) =3773415a(22) =8686867a(23) =20072822a(24) =46541053a(25) =108241285a(26) =252447554a(27) =590284775a(28) =1383498325a(29) =3249679480