English
For m,n ∈ ℕ, uniformBell(m,n) equals the product over p from 0 to m−1 of binomial(p·n + n − 1, n − 1).
Русский
Для всех m,n ∈ ℕ имеет место равенство: uniformBell(m,n) = ∏_{p=0}^{m-1} C(p·n + n − 1, n − 1).
LaTeX
$$$ \\mathrm{uniformBell}(m,n) = \\prod_{p \\in \\{0,1,\\dots,m-1\\}} {pn + n - 1 \\choose n - 1} $$$
Lean4
/-- Number of possibilities of dividing a set with `m * n` elements into `m` groups
of `n`-element subsets. -/
def uniformBell (m n : ℕ) : ℕ :=
bell (replicate m n)