Sum of the numerators for computing the second moment of the probability mass function (PMF) of the number of 2-cycles in the involutions on n elements (A000085) assuming the involutions are all equally likely.
A174764
Sum of the numerators for computing the second moment of the probability mass function (PMF) of the number of 2-cycles in the involutions on n elements (A000085) assuming the involutions are all equally likely.
Terms
- a(0) =0a(1) =1a(2) =3a(3) =18a(4) =70a(5) =330a(6) =1386a(7) =6328a(8) =28008a(9) =130140a(10) =603460a(11) =2895816a(12) =14024088a(13) =69786808a(14) =352043160a(15) =1817317440a(16) =9525774016a(17) =50958843408a(18) =276906491568
External references
- oeis: A174764