Арифметическая и геометрическая прогрессии. Arithmetical and Geometrical Progressions
An arithmetical progression is a sequence such as 3, 5, 7, 9 …, in which each member differs from the one in front of it by the same amount.
A geometrical progression is a sequence such as 3, 6, 12, 24 …, in which each member differs from the one in the same ratio. “The number of families holidaying abroad grew now in geometrical progression”.
Mathematicians more often use now the expressions arithmetic sequence and geometric sequence.