Number of hill-free Dyck paths of semilength n+3 and having no peaks at level 2 (a Dyck path is said to be hill-free if it has no peaks at level 1).

A114627

Number of hill-free Dyck paths of semilength n+3 and having no peaks at level 2 (a Dyck path is said to be hill-free if it has no peaks at level 1).

Terms

    a(0) =1a(1) =2a(2) =6a(3) =19a(4) =61a(5) =202a(6) =683a(7) =2348a(8) =8184a(9) =28855a(10) =102731a(11) =368813a(12) =1333684a(13) =4853436a(14) =17761181a(15) =65320691a(16) =241300829a(17) =894958140a(18) =3331323651a(19) =12441078958a(20) =46601721324a(21) =175040968111a(22) =659136721385

External references