Siman 642
Presented here for study, not as a practical ruling. The Shulchan Aruch rules by Sephardi custom, the Rema's glosses by Ashkenazi custom, and the Kitzur follows Ashkenazi custom. For a practical question, ask your rabbi.
א אִם חָל יוֹם רִאשׁוֹן שֶׁל סֻכּוֹת לִהְיוֹת בְּשַׁבָּת, אוֹמְרִים בְּעַרְבִית בְּרָכָה אַחַת מֵעֵין שֶׁבַע וְחוֹתֵם בָּהּ בְּשַׁבָּת בִּלְבַד.
1 When the first night of Sukkot falls on Shabbos, one recites the one blessing that summarizes the seven blessings of Shemoneh Esreh, and ends it with Shabbos only.