2701440

Appears in sequences

• 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=8A225108
• E.g.f. satisfies A(x)^A(x) = 1/(1 - x)^(x^2).at n=10A356910