A website's daily hits double each day and the model gives a_n = 2^n. How many hits does the model predict on day 31?

1. The explicit formula a_n = 2^n gives the term at position n directly, with no need to list earlier terms. 2. Day 31 means n = 31, so the value wanted is 2^31. 3. 2^31 = 2,147,483,648, which is just over 2.1 billion hits. 4. 2^30 = 1,073,741,824 is the day 30 figure, and 2^32 = 4,294,967,296 belongs to day 32, so both are off by one day. _Source: OpenStax Algebra and Trigonometry (CC BY 4.0), Ch 13 "Sequences, Probability and Counting Theory", section 13.1 Sequences and Their Notations_