Is a rak'ah counted if the Imam prostrates for forgetfulness while the worshipper is prostrating behind him?

If the Imam performs the prostration of forgetfulness (sujud al-sahw), the latecomer (masbuq) must follow him in his prostration. This following is not considered an addition to the worshipper's prayer, nor does it count as a complete bowing (rak'ah). If you catch the bowing of the last rak'ah with the Imam, then you have caught the rak'ah. You then follow him in the prostration of forgetfulness, and thereafter, you stand to complete what you missed of the prayer after he performs the tasleem.