6th-largest term in n-th row of Stern's diatomic triangle A002487.

Terms

a(0) =2a(1) =8a(2) =15a(3) =26a(4) =45a(5) =75a(6) =121a(7) =199a(8) =322a(9) =542a(10) =877a(11) =1427a(12) =2309a(13) =3739a(14) =6050a(15) =9790a(16) =15841a(17) =25632a(18) =41473a(19) =67105a(20) =108578a(21) =175683a(22) =284261a(23) =459944a(24) =744205a(25) =1204149a(26) =1948354a(27) =3152503a(28) =5100857a(29) =8253360