Floor(Fibonacci(2n+1)/9).

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =3a(5) =9a(6) =25a(7) =67a(8) =177a(9) =464a(10) =1216a(11) =3184a(12) =8336a(13) =21824a(14) =57136a(15) =149585a(16) =391619a(17) =1025273a(18) =2684201a(19) =7027331a(20) =18397793a(21) =48166048a(22) =126100352a(23) =330135008a(24) =864304672a(25) =2262779008a(26) =5924032352a(27) =15509318049a(28) =40603921795a(29) =106302447337