Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k cycles that are not up-down. A cycle (b(1), b(2), ...) is said to be up-down if, when written with its smallest element in the first position, it satisfies b(1)<b(2)>b(3)<... .

A186361

Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k cycles that are not up-down. A cycle (b(1), b(2), ...) is said to be up-down if, when written with its smallest element in the first position, it satisfies b(1)<b(2)>b(3)<... .

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =1a(5) =16a(6) =8a(7) =61a(8) =59a(9) =272a(10) =438a(11) =10a(12) =1385a(13) =3445a(14) =210a(15) =7936a(16) =29080a(17) =3304a(18) =50521a(19) =264871a(20) =47208a(21) =280a(22) =353792a(23) =2605002a(24) =658806a(25) =11200a(26) =2702765a(27) =27634817a(28) =9275838a(29) =303380

External references