The FIA Formula 1 World Championship entry list does not have a number 13. The number is generally considered to be an unlucky number. It was used in the early years of the sport but in the 1920s it was dropped after the Delage factory team suffered two fatal accidents with the number in the course of just a few months. The first was Paul Torchy, who crashed into a tree during the San Sebastian Grand Prix in September 1925.
That was the last major international event of the year and the Delage factory team did not reappear until the Targa Florio in Sicily in April 1926. Italian Count Giulio Masetti was in the number 13 on that occasion and was killed when his car went up an embankment and overturned near the village of Sclafani Bagni, near Caltavuturo. He was crushed beneath the car.
The second occasion was in 1976 when Divina Galica tried to qualify for the British Grand Prix in a Surtees entered by Nick Whiting, brother of the FIA’s Formula 1 Race Director Charlie Whiting. She failed to qualify.
Other countries have unlucky numbers, notably the Japanese. They do not think the number 4 is lucky. Thus when Tyrrell employed Satoru Nakajima and later Ukyo Katayama both raced the number 3.