Fix NaN error when n>300

I need to write the following equation so that it works when n is anything greater than 300. It currently works for anythig 300 or less but anything greater I get NaN.

Formula written into code: .

Current code:

n=100;

numerator=1;
for i=n:-2:2
    numerator=numerator*i;
end

denominator=1;
for i=n-1:-2:1
    denominator=denominator*i;
end

%percision 10^-4
digits(6);

%calculate r
R=numerator/denominator;
disp(R)

Answer 1

[KSSV]

If you have symbolic toolbox use vpa. REad about it.

n=701;

numerator=vpa(1);
for i=n:-2:2
    numerator=numerator*i;
end

denominator=vpa(1);
for i=n-1:-2:1
    denominator=denominator*i;
end

%percision 10^-4
digits(6);

%calculate r
R=numerator/denominator;
disp(R)

21.1326