Number puzzle game

In the puzzle, you must continue a series of numbers according to certain rules

Each next number in the series must correspond to a certain formula. For example, in a number series: 1 → 3 → 5 →? - the next number should be 7, since 2 (x + 2) is added to the previous number.

The game has 50 levels and as you progress through the difficulty will increase, and the formulas will be more difficult.