Din teorema impartirii cu rest :
x = 13 *c + 2c, unde 2c < 13, deci c < 7
Daca c = 1
x = 13*1 + 2 = 15
Daca c=2
x = 13*2 + 4 = 30
Daca c=3
x=13*3+6 = 45
Daca c=4
x=13*4 + 8 = 60
Daca c=5
x=13*5+10 = 75
Daca c=6
x=13*6+ 12 = 90
Deci numerele sunt 15, 30, 45, 60, 75, 90
