Number of 4-power-free binary words of length n.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =14a(5) =26a(6) =48a(7) =88a(8) =160a(9) =292a(10) =532a(11) =972a(12) =1768a(13) =3220a(14) =5866a(15) =10686a(16) =19454a(17) =35430a(18) =64528a(19) =117520a(20) =214004a(21) =389724a(22) =709730a(23) =1292496a(24) =2353758a(25) =4286442a(26) =7806048a(27) =14215620a(28) =25888034a(29) =47144704