a(n) = 8*Fibonacci(2n+1).

Terms

a(0) =8a(1) =16a(2) =40a(3) =104a(4) =272a(5) =712a(6) =1864a(7) =4880a(8) =12776a(9) =33448a(10) =87568a(11) =229256a(12) =600200a(13) =1571344a(14) =4113832a(15) =10770152a(16) =28196624a(17) =73819720a(18) =193262536a(19) =505967888a(20) =1324641128a(21) =3467955496a(22) =9079225360a(23) =23769720584a(24) =62229936392a(25) =162920088592a(26) =426530329384