Fibonacci sequence

A  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)

Behind the scenes
Though unremarked in Daisy Chain or Flatline, the first eight Fibonacci numbers are 1, 1, 2, 3, 5, 8, 13 and 21.