n4+4=n4+4n2+4-4n2=(n^2+2)^2-(2n)^2=(n^2+2n+2)(n^2-2n+2)=((n+1)^2+1)((n-1)^2+1)
=>P =\(\frac{\left(1^2+1\right)\left(3^2+1\right)...\left(2013^2+1\right)\left(2015^2+1\right)}{\left(3^2+1\right)\left(5^2+1\right)...\left(2015^2+1\right)\left(2017^2+1\right)}=\frac{2}{2017^2+1}\)