Triangle read by rows: T(n, k) = number of matchings of 2n people with partners (of either sex) such that exactly k couples are left together.

A055140

Triangle read by rows: T(n, k) = number of matchings of 2n people with partners (of either sex) such that exactly k couples are left together.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =2a(4) =0a(5) =1a(6) =8a(7) =6a(8) =0a(9) =1a(10) =60a(11) =32a(12) =12a(13) =0a(14) =1a(15) =544a(16) =300a(17) =80a(18) =20a(19) =0a(20) =1a(21) =6040a(22) =3264a(23) =900a(24) =160a(25) =30a(26) =0a(27) =1a(28) =79008a(29) =42280

External references