n=2018+2*(1+2+3+...+2017) (- Aplicam formula Sumei lui Gauss)
Suma lui gauss: 1 + 2 + 3 + 4 + … + n = n x ( n + 1 ) / 2
n=2018+2*[2017*(2017+1)/2]
n=2018+2*(2017*2018/2) (-Se simplifica 2-ul)
n=2018+2017*2018 (-Scoatem factor comun 2018)
n=2018(1+2017)=2018*2018
n=2018^2, deci n=Patrat perfect