Problem Statement

The factorial of a number, written as

n !

{\displaystyle n!}

, is defined as

n !

n ( n − 1 ) ( n − 2 ) . . . ( 2 ) ( 1 )

{\displaystyle n!=n(n-1)(n-2)...(2)(1)}

. Multifactorials generalize factorials as follows: In all cases, the terms in the products are positive integers. If we define the degree of the multifactorial as the difference in successive terms that are multiplied together for a multifactorial (the number of exclamation marks), then the task is twofold:

Note: The wikipedia entry on multifactorials gives a different formula. This task uses the Wolfram mathworld definition.

Let's start with the solution:

procedure main(A)
    l := integer(A[1]) | 10
    every writeRow(n := !l, [: mf(!10,n) :])
end

procedure writeRow(n, r)
    writes(right(n,3),": ")
    every writes(right(!r,8)|"\n")
end

procedure mf(n, m)
    if n <= 0 then return 1
    return n*mf(n-m, m)
end