A G-rich core sequence G3-TCA-G3-T1,2-G3-T1,2-G3 can be designed to fold into a parallel or into two different (3+1) hybrid-type G-quadruplexes, among them an elusive topology with one lateral followed by two propeller loops. Favored folds can be rationalized based on the number of intervening thymidines and on additional complementary flanking sequences.