130288435200
domain: N
Appears in sequences
- a(n) = phi(binomial(2*n,n)*n^2).at n=17A131681
- Number of pairs (x,y) of elements x of the symmetric group S_{n-1} and y of the symmetric group S_{n} that commute. Here the symmetric group S_{n-m} is to be thought of as the subgroup of the symmetric group S_n which stabilizes n-m+1,n-m+2,...n.at n=12A225108