Irregular triangle read by rows: T(n,k) is the number of permutations in C_n (= the 1-cycles in S_n) having k stretching pairs.

A216121

Irregular triangle read by rows: T(n,k) is the number of permutations in C_n (= the 1-cycles in S_n) having k stretching pairs.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =5a(4) =1a(5) =16a(6) =6a(7) =2a(8) =63a(9) =31a(10) =20a(11) =5a(12) =1a(13) =294a(14) =168a(15) =150a(16) =70a(17) =30a(18) =6a(19) =2a(20) =1585a(21) =997a(22) =1072a(23) =691a(24) =423a(25) =171a(26) =75a(27) =20a(28) =5a(29) =1

External references