I don't believe that a single tree is sufficient. Here's my reasoning:

You gain energy by burning fuel (food) that you combine with oxygen to release carbon dioxide and water. You need to eat a certain amount of fuel per day in order to life, and the amount of oxygen that you need is the amount of oxygen needed to burn that much fuel.

In order to release oxygen, a plant has to take the other parts of the carbon dioxide and water that it is using to do this and create sugars, i.e. fuel. These sugars are solid, and are added to the plant's body, which can be seen by the growth of the plant. The amount of oxygen that is released is the exact same amount of oxygen required to burn that fuel and turn it back into carbon dioxide and water.

Therefore, in order to produce as much oxygen as you consume, the plant would have to grow at a rate at which you must eat, which is roughly 500 grams per day. I don't believe that redwoods or other fast-growing trees are capable of growing that fast.