un término n de una sucesión aritmética = an = a₁+(n-1)d
a₁ = 1/2. d=1/3
a₂ = 1/2+(2-1)1/3 = 1/2+1/3 = (3+2)/6 = 5/6
a₃ = 1/2+(3-1)1/3 = 1/2+2/3 = (3+4)/6 = 7/6
a₄ = 1/2+(4-1)1/3 = 1/2+3/3 = (3+6) = 9/6 = 3/2
a₅ = 1/2+(5-1)1/3 = 1/2+4/3 = (3+8) = 11/3
....
a₁₀ = 1/2+(10-1)1/3 = 1/2+9/3 = 1/2+2 = (1+4)/2 = 5/2
