Number of Dyck paths of semilength n such that each positive level up to the highest nonempty level has exactly two peaks.

A287845

Number of Dyck paths of semilength n such that each positive level up to the highest nonempty level has exactly two peaks.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =0a(4) =0a(5) =3a(6) =6a(7) =0a(8) =9a(9) =54a(10) =138a(11) =207a(12) =360a(13) =1368a(14) =4545a(15) =11304a(16) =25182a(17) =61605a(18) =173916a(19) =498798a(20) =1347417a(21) =3497328a(22) =9147060a(23) =24630669a(24) =67414590a(25) =184065966a(26) =498495303a(27) =1345622436a(28) =3642036804a(29) =9900361107

External references