Triangle read by rows: T(n,k) is the number of down-up permutations on [n] with k left-to-right maxima.

A098906

Triangle read by rows: T(n,k) is the number of down-up permutations on [n] with k left-to-right maxima.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =3a(6) =5a(7) =8a(8) =3a(9) =16a(10) =30a(11) =15a(12) =61a(13) =121a(14) =75a(15) =15a(16) =272a(17) =588a(18) =420a(19) =105a(20) =1385a(21) =3128a(22) =2478a(23) =840a(24) =105a(25) =7936a(26) =18960a(27) =16380a(28) =6300a(29) =945

External references