Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k increasing even cycles (0<=k<=n). A cycle (b(1), b(2), ...) is said to be increasing if, when written with its smallest element in the first position, it satisfies b(1)<b(2)<b(3)<... . A cycle is said to be even if it has an even number of entries. For example, the permutation (18)(2347)(569) has 2 increasing even cycles.

A186764

Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k increasing even cycles (0<=k<=n). A cycle (b(1), b(2), ...) is said to be increasing if, when written with its smallest element in the first position, it satisfies b(1)<b(2)<b(3)<... . A cycle is said to be even if it has an even number of entries. For example, the permutation (18)(2347)(569) has 2 increasing even cycles.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =3a(5) =3a(6) =14a(7) =7a(8) =3a(9) =70a(10) =35a(11) =15a(12) =419a(13) =226a(14) =60a(15) =15a(16) =2933a(17) =1582a(18) =420a(19) =105a(20) =23421a(21) =12741a(22) =3423a(23) =630a(24) =105a(25) =210789a(26) =114669a(27) =30807a(28) =5670a(29) =945

External references