a^2+a^2 * (a+1)^2 + (a+1)^2
=(a^2+1) * ((a+1)^2+1) - 1
=(a^2+1) * (a^2 + 2a +2) -1
=a^4 + 2a^3 + 3a^2 +2a + 1
=(a^2 + a + 1) ^2
把a=2002代入,a^2 + a + 1 = 4010007