Salut,
a1+a2+a3+...+an=
[2(1)-1] +[2(2)-1]+[2(3)-1]+...+[2(n)-1]=
extragem 2 si stiim catoti -1 adunati dau -n
2(1+2+3+...+n)-n =
[tex] 2(\frac{n(n+1)}{2}) -n = 2016^{2} [/tex]
=[tex] n^{2} +n-n= 2016^{2} [/tex]
[tex] n^{2} = 2016^{2} [/tex]
deci n=2016
