Fibonacci sequence
A Fibonacci sequence was a sequence of numbers that included 34, 55, and 89. (PROSE: Daisy Chain) The Twelfth Doctor identified 55 as the tenth Fibonacci number. (TV: Flatline)
According to Saul, daisies had petal numbers in line with the Fibonacci sequence. (PROSE: Daisy Chain)
When Professor Jeffrey Broderick received a bottle of malt laced with a hallucinogen from Sir Toby Kinsella in 1964, it caused him to recite the Fibonacci sequence ad infinitum in order to keep himself occupied. (AUDIO: Artificial Intelligence)
The Weave's life cycle was similar to a Fibonacci sequence, with each name a successive number added to the last. When the Eleventh Doctor met a Weave named 6011, she confirmed that the Weave before her was 3715, and the one after her was 9726. (PROSE: The Glamour Chase)