81648000

Appears in sequences

• a(n) = n! * n(n-1)/4.at n=10A001809
• Array of coefficients of denominator polynomials of the n-th approximation of the continued fraction x/(1+x/(2+x/(3+..., related to Laguerre polynomial coefficients.at n=44A084950
• Triangle read by rows: T(n,k) is the number of fixed-point-free involutions of {1,2,...,2n} having k cycles with entries of opposite parities (0 <= k <= n).at n=63A161119
• Triangle read by rows: T(n,k) is the number of fixed-point-free involutions of {1,2,...,2n} having k cycles with entries of the same parity (0 <= k <= 2*floor(n/2)).at n=52A161121
• Number of non-attacking placements of 8 rooks on an n X n board.at n=9A179063
• Number of n-digit numbers in base ten having at least five different digits with no leading zeros allowed.at n=3A268358
• Numbers that set records in in A379772.at n=33A379773