Number of unimodal maps [1..n]->[0..3].

Terms

a(0) =1a(1) =4a(2) =16a(3) =50a(4) =130a(5) =296a(6) =610a(7) =1163a(8) =2083a(9) =3544a(10) =5776a(11) =9076a(12) =13820a(13) =20476a(14) =29618a(15) =41941a(16) =58277a(17) =79612a(18) =107104a(19) =142102a(20) =186166a(21) =241088a(22) =308914a(23) =391967a(24) =492871a(25) =614576a(26) =760384a(27) =933976a(28) =1139440a(29) =1381300