Triangle read by rows: T(n,k) is the number of permutations of [n] having k cycles with 2 alternating runs (it is assumed that the smallest element of the cycle is in the first position), 0<=k<=floor(n/3).

A187244

Triangle read by rows: T(n,k) is the number of permutations of [n] having k cycles with 2 alternating runs (it is assumed that the smallest element of the cycle is in the first position), 0<=k<=floor(n/3).

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =1a(5) =17a(6) =7a(7) =78a(8) =42a(9) =463a(10) =247a(11) =10a(12) =3315a(13) =1550a(14) =175a(15) =27164a(16) =11049a(17) =2107a(18) =247975a(19) =92596a(20) =22029a(21) =280a(22) =2492539a(23) =906427a(24) =220734a(25) =9100a(26) =27422698a(27) =10044963a(28) =2264724a(29) =184415

External references