How many sequels to I, Claudius (1934) did Robert Graves write?

Robert Graves wrote one sequel to I, Claudius, Claudius the God, published in 1934.

It charts Claudius’s rule from 41 A.D. until his poisoning by his wife Agrippina in 54 A.D.

What was the last sequel to Planet of the Apes (1968)? Battle for the Planet of the Apes (1973) was the last sequel to Planet of the Apes (1968).
At what address were the stairs in the TV show “Upstairs, Downstairs” (PBS, 1974-79)? The stairs in the TV show "Upstairs, Downstairs" were at 165 Eaton Place in London. The house actually filmed was No. 65, but to avoid lawsuits, the producers glued a "1" in front…
Who represents Agamemnon in Eugene O’Neill’s Mourning Becomes Electra (1931)? Ezra Mannon, a New England general returning from the Civil War represents Agamemnon in Eugene O'Neill's Mourning Becomes Electra. His wife Christine represents Clytemnestra.
In what movie does the line “The natives are restless tonight” first appear? The Island of Lost Souls (1933) was the first movie with the line "The natives are restless tonight". It is said by Charles Laughton.
When did Washington Irving (1783-1859) court Mary Shelley (1797-1851)? Washington Irving and fellow American writer John H. Payne were said to have competed for the affection of the author of Frankenstein during a visit to France from 1824 to 1826. Mary's husband…
How many Pulitzer prizes did Eugene O’Neill win? Eugene O'Neill won four Pulitzer prizes, for Beyond the Horizon (1920), Anna Christie (1922), Strange Interlude (1928), and Long Day's Journey into Night (1957).