a(n) = a(n-1) + a(n-2) + 1, with a(0) = 1 and a(1) = 12.

Terms

a(0) =1a(1) =12a(2) =14a(3) =27a(4) =42a(5) =70a(6) =113a(7) =184a(8) =298a(9) =483a(10) =782a(11) =1266a(12) =2049a(13) =3316a(14) =5366a(15) =8683a(16) =14050a(17) =22734a(18) =36785a(19) =59520a(20) =96306a(21) =155827a(22) =252134a(23) =407962a(24) =660097a(25) =1068060a(26) =1728158a(27) =2796219a(28) =4524378a(29) =7320598