Triangle T(n,k) giving number of degree-2n permutations which decompose into exactly k cycles of even length, k=0..n.
A204420
Triangle T(n,k) giving number of degree-2n permutations which decompose into exactly k cycles of even length, k=0..n.
Terms
- a(0) =1a(1) =0a(2) =1a(3) =0a(4) =6a(5) =3a(6) =0a(7) =120a(8) =90a(9) =15a(10) =0a(11) =5040a(12) =4620a(13) =1260a(14) =105a(15) =0a(16) =362880a(17) =378000a(18) =132300a(19) =18900a(20) =945a(21) =0a(22) =39916800a(23) =45571680a(24) =18711000a(25) =3534300a(26) =311850a(27) =10395a(28) =0a(29) =6227020800
External references
- oeis: A204420