a(n) = A098601(2n) + A098601(2n+1).

Terms

a(0) =2a(1) =3a(2) =4a(3) =7a(4) =13a(5) =23a(6) =40a(7) =70a(8) =123a(9) =216a(10) =379a(11) =665a(12) =1167a(13) =2048a(14) =3594a(15) =6307a(16) =11068a(17) =19423a(18) =34085a(19) =59815a(20) =104968a(21) =184206a(22) =323259a(23) =567280a(24) =995507a(25) =1746993a(26) =3065759a(27) =5380032a(28) =9441298a(29) =16568323