For examples;
N20 (Dinitrogen oxide)
Pb3O (Tripumbulic oxide)
C3O2 (carbon suboxide)
C12O9 (Maletic anhydride or oxide) etc.
The structure of carbon suboxide has been the subject of experimental and it may be assume all the carbon in C3O2 are arranged in linear pattern and sp hybridised and its structure is look like as.
O=C=C=C=O