a₁ = 2

a₂ = 3

aₙ = 29

r = razao

r = a₂ - a₁

r = 3 - 2

r = 1

Termo geral: aₙ = a₁ + (n-1).r

29 = 2 + (n-1) . 1

29 - 2 = n - 1

n = 29 - 2 + 1

n = 28 termos