Răspuns:
n x n+1 :2
[tex]n^{2}[/tex]+1 :2
n= 3,5,7,9
[tex]3^{2} +1=9+1=10 (divizibil-la-2)\\5^{2} +1=25+1=26 (divizibil-la-2)\\7^{2} +1=49+1=50 (divizibil-la-2)\\9^{2} +1=81+1=90 (divizibil-la-2)\\[/tex]
