a(n) = a(n-1) + a(n-2) + 1, with a(0) = 1 and a(1) = 6.

Terms

a(0) =1a(1) =6a(2) =8a(3) =15a(4) =24a(5) =40a(6) =65a(7) =106a(8) =172a(9) =279a(10) =452a(11) =732a(12) =1185a(13) =1918a(14) =3104a(15) =5023a(16) =8128a(17) =13152a(18) =21281a(19) =34434a(20) =55716a(21) =90151a(22) =145868a(23) =236020a(24) =381889a(25) =617910a(26) =999800a(27) =1617711a(28) =2617512a(29) =4235224