This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 0 |
| 4 | 10 |
| 5 | 7 |
| 6 | 0 |
| 7 | 73 |
| 8 | 46 |
| 9 | 0 |
| 10 | 56 |
| 11 | 219 |
| 12 | 0 |
| 13 | 25 |
| 14 | 60 |
| 15 | 0 |
| 16 | 52 |
| 17 | 117 |
| 18 | 0 |
| 19 | 535 |
| 20 | 172 |
| 21 | 0 |