Triangle read by rows: T(n,k) is the number of cycle-up-down permutations of {1,2,...,n} having k excedances (0<=k<=floor(n/2)).

A186368

Triangle read by rows: T(n,k) is the number of cycle-up-down permutations of {1,2,...,n} having k excedances (0<=k<=floor(n/2)).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =4a(6) =1a(7) =10a(8) =5a(9) =1a(10) =20a(11) =40a(12) =1a(13) =35a(14) =175a(15) =61a(16) =1a(17) =56a(18) =560a(19) =768a(20) =1a(21) =84a(22) =1470a(23) =4996a(24) =1385a(25) =1a(26) =120a(27) =3360a(28) =22720a(29) =24320

External references