Related Clues:

• Mathematical sequence related to a pattern found in a 17-, 29-, 42- or 58-Across, informally
• one, one, two, three, five, eight, thirteen etc
• Sequence of numbers in which each number is the sum of the previous two
• 1, 1, 2, 3, 5, 8, 13, 21, etc
• 1, 1, 2, 3, 5, 8, 13, 21, 34, and so on