Name a lanthanoid element which exhibits +4 oxidation state besides +3 oxidation state.

Explanation

To answer the question, we need to identify a lanthanoid element that exhibits both +3 and +4 oxidation states.

### Step-by-Step Solution:

1. **Identify Lanthanoids**: The lanthanoid series consists of 15 elements from lanthanum (La) to lutetium (Lu). These elements are known for their variable oxidation states, primarily +3.

2. **Check for +4 Oxidation State**: Among the lanthanoids, most elements predominantly exhibit a +3 oxidation state. However, we need to find one that can also exhibit a +4 oxidation state.

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