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

Terms

a(0) =1a(1) =1a(2) =6a(3) =12a(4) =24a(5) =43a(6) =75a(7) =127a(8) =212a(9) =350a(10) =574a(11) =937a(12) =1525a(13) =2477a(14) =4018a(15) =6512a(16) =10548a(17) =17079a(18) =27647a(19) =44747a(20) =72416a(21) =117186a(22) =189626a(23) =306837a(24) =496489a(25) =803353a(26) =1299870a(27) =2103252a(28) =3403152a(29) =5506435