Generalized Fibonacci numbers D_{n,3}.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =4a(5) =8a(6) =16a(7) =32a(8) =64a(9) =130a(10) =264a(11) =538a(12) =1104a(13) =2272a(14) =4692a(15) =9730a(16) =20236a(17) =42208a(18) =88288a(19) =185126a(20) =389072a(21) =819458a(22) =1729296a(23) =3655936a(24) =7742124a(25) =16420928a(26) =34879040a(27) =74185364a(28) =157986068a(29) =336845482