Number of Dyck paths of semilength n such that each positive level has exactly four peaks.

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =1a(5) =0a(6) =0a(7) =0a(8) =0a(9) =5a(10) =45a(11) =105a(12) =70a(13) =0a(14) =25a(15) =525a(16) =4950a(17) =26950a(18) =94605a(19) =226925a(20) =383525a(21) =507000a(22) =1016475a(23) =5047875a(24) =26940475a(25) =117108550a(26) =414703200a(27) =1223146475a(28) =3089625550a(29) =7073320775