a(n) = Fibonacci(n) - 1.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =4a(5) =7a(6) =12a(7) =20a(8) =33a(9) =54a(10) =88a(11) =143a(12) =232a(13) =376a(14) =609a(15) =986a(16) =1596a(17) =2583a(18) =4180a(19) =6764a(20) =10945a(21) =17710a(22) =28656a(23) =46367a(24) =75024a(25) =121392a(26) =196417a(27) =317810a(28) =514228a(29) =832039