Code for generating the Sheeran Numbers.
We define a Sheeran Number to be: any number which can be made using the three Ed Sheeran albums, + (2011), × (2014) and ÷ (2017), along with four other numbers which are also the names of distinct UK number one albums in Ed Sheeran's lifetime (since February 1991). The order of operator precedence is given by: the most recent album is resolved first, then proceed backwards towards the earliest album. In this case I'm considering only numbers that are made using all three operators (in some order) and four number albums.
The numerical albums permitted within the given date range are: 1 (The Beatles), 3 (Take That), 4 (Beyoncé), 4 (One Direction), 5 (5ive), 7 (S Club 7), 13 (Blur), 13 (Black Sabbath), 18 (Moby), 19 (Adele), 21 (Adele), 25 (Adele), 25 (George Michael), 50 (Rick Astley), 1977 (Ash), 1989 (Taylor Swift) and 8701 (Usher). Note that three numbers occur twice in this list (4, 13, 25), and hence they are the only ones allowed to be used more than once.
The data I've generated indicates there are over 22,000 Sheeran numbers, but 1 is not a Sheeran Number. The smallest Sheeran Number is 1.001379152, calculated as 1+(3×(4÷8701)), and the largest is 17308266, calculated as (1977÷1)+(1989×8701). Also, there are 8 ways to make the number 2. 0 is not possible, and probably won't be until Ed Sheeran releases an album called -. The jury is still out on whether the Robson and Jerome album Take Two would be allowed as a -2 functor.
Future improvements It might be useful to also calculate numbers which can be made using fewer than four number albums and not all three Sheeran albums, which would make it possible to make 1.