a(0)=0: a(n)=A002865(2*n)+A002865(2*n+1), n>=1.

Terms

a(0) =0a(1) =2a(2) =4a(3) =8a(4) =15a(5) =26a(6) =45a(7) =75a(8) =121a(9) =193a(10) =302a(11) =463a(12) =703a(13) =1052a(14) =1555a(15) =2277a(16) =3301a(17) =4740a(18) =6754a(19) =9548a(20) =13398a(21) =18678a(22) =25873a(23) =35620a(24) =48771a(25) =66418a(26) =89988a(27) =121345a(28) =162878a(29) =217666