Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having exactly k even fixed points (0 <= k <= floor(n/2)).

A161134

Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having exactly k even fixed points (0 <= k <= floor(n/2)).

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =2a(6) =14a(7) =8a(8) =2a(9) =78a(10) =36a(11) =6a(12) =426a(13) =234a(14) =54a(15) =6a(16) =3216a(17) =1512a(18) =288a(19) =24a(20) =24024a(21) =12864a(22) =3024a(23) =384a(24) =24a(25) =229080a(26) =108960a(27) =22320a(28) =2400a(29) =120

External references