f := proc (n, m)
	local fac, i;
	fac := 1;
	for i from n by -m to 1 do
		fac := fac*i;
	end do;
	return fac;
end proc:

a:=Matrix(5,10):
for i from 1 to 5 do
	for j from 1 to 10 do
		a[i,j]:=f(j,i);
	end do;
end do;
a;