Number of Dean words of length n, i.e., squarefree reduced words over {0,1,2,3}.

Terms

a(0) =4a(1) =8a(2) =16a(3) =24a(4) =40a(5) =64a(6) =104a(7) =144a(8) =216a(9) =328a(10) =496a(11) =720a(12) =1072a(13) =1584a(14) =2344a(15) =3384a(16) =4952a(17) =7264a(18) =10632a(19) =15504a(20) =22656a(21) =33136a(22) =48488a(23) =70592a(24) =103032a(25) =150352a(26) =219400a(27) =319816a(28) =466664a(29) =680872