For example, 9 is a D-number since it divides all the numbers , , , and .
The smallest 3 × 3 magic square whose entries are D-numbers is
87 | 267 | 69 |
123 | 141 | 159 |
213 | 15 | 195 |
Below, the spiral pattern of D-numbers up to . See the page on prime numbers for an explanation and links to similar pictures.
The first D-numbers are 9, 15, 21, 33, 39, 51, 57, 63, 69, 87, 93, 111, 123, 129, 141, 159, 177, 183, 195, 201, 213, 219 more terms