There are four places in the Quran where it is wajib to perform a sajdah after reciting it, or hearing it. They are in the surahs that are called Suwar al-'Aza`im.
1. Surah Sajdah, verse 15.
2. Surah Ha`-Mim/Fussilat, verse 38.
3. Surah Najm, verse 62.
4. Surah al-"Alaq, verse 19.
And Allah knows best.