Number of prefix normal words of length n.

Terms

a(0) =2a(1) =3a(2) =5a(3) =8a(4) =14a(5) =23a(6) =41a(7) =70a(8) =125a(9) =218a(10) =395a(11) =697a(12) =1273a(13) =2279a(14) =4185a(15) =7568a(16) =13997a(17) =25500a(18) =47414a(19) =87024a(20) =162456a(21) =299947a(22) =562345a(23) =1043212a(24) =1962589a(25) =3657530a(26) =6900717a(27) =12910042a(28) =24427486a(29) =45850670