7783776000

Appears in sequences

• a(n)=2*n!/d(n!); d(m)=A000005(m) is the number of divisors of m.at n=16A125721
• 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=11A225108