Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} with k parity changes (n>=2; 1<=k <=n-1); the permutation 372185946 has 5 parity changes: 37-2-1-8-59-46.

A152874

Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} with k parity changes (n>=2; 1<=k <=n-1); the permutation 372185946 has 5 parity changes: 37-2-1-8-59-46.

Terms

    a(0) =2a(1) =4a(2) =2a(3) =8a(4) =8a(5) =8a(6) =24a(7) =36a(8) =48a(9) =12a(10) =72a(11) =144a(12) =288a(13) =144a(14) =72a(15) =288a(16) =720a(17) =1728a(18) =1296a(19) =864a(20) =144a(21) =1152a(22) =3456a(23) =10368a(24) =10368a(25) =10368a(26) =3456a(27) =1152a(28) =5760a(29) =20160

External references