Number of ways to group the first 2*n natural numbers into n pairs (xi, yi) such that the n numbers xi + yi are all different.
A320129
Number of ways to group the first 2*n natural numbers into n pairs (xi, yi) such that the n numbers xi + yi are all different.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =10a(4) =55a(5) =412a(6) =3736a(7) =40518a(8) =505486a(9) =7145031a(10) =112844566a(11) =1970286922a(12) =37676184205
External references
- oeis: A320129