function [result]=rv_HW(x1,x2,x3)
n=x1+x2+x3;
parte1=factorial(n+2)*factorial(2*x1+x2)*factorial(2*x3+x2)*2^(x2-1)/(factorial(x1)*factorial(x2)*factorial(x3)*factorial(2*n+1)*3);
parte2=5-12*(2*x1+x2+1)*(2*x3+x2+1)/((2*n+2)*(2*n+3));
result=parte1*parte2;
