a(n) = a(n-1) + a(n-2) + 1 for n>1, a(0)=0, a(1)=3.

Terms

a(0) =0a(1) =3a(2) =4a(3) =8a(4) =13a(5) =22a(6) =36a(7) =59a(8) =96a(9) =156a(10) =253a(11) =410a(12) =664a(13) =1075a(14) =1740a(15) =2816a(16) =4557a(17) =7374a(18) =11932a(19) =19307a(20) =31240a(21) =50548a(22) =81789a(23) =132338a(24) =214128a(25) =346467a(26) =560596a(27) =907064a(28) =1467661a(29) =2374726