Triangle read by rows: T(n,k) is the number of up-down permutations of {1,2,...,n} having genus k (see first comment for definition of genus).

A178516

Triangle read by rows: T(n,k) is the number of up-down permutations of {1,2,...,n} having genus k (see first comment for definition of genus).

Terms

    a(0) =1a(1) =1a(2) =0a(3) =2a(4) =0a(5) =0a(6) =2a(7) =3a(8) =0a(9) =0a(10) =6a(11) =10a(12) =0a(13) =0a(14) =0a(15) =6a(16) =38a(17) =17a(18) =0a(19) =0a(20) =0a(21) =22a(22) =142a(23) =104a(24) =4a(25) =0a(26) =0a(27) =0a(28) =22a(29) =351

External references