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) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 23 |
| 4 | 175 |
| 5 | 1678 |
| 6 | 19579 |
| 7 | 270683 |
| 8 | 4342447 |
| 9 | 79498622 |
| 10 | 1638471038 |
| 11 | 37592670383 |
| 12 | 951214496814 |
| 13 | 26333793485772 |
| 14 | 792232525678756 |
| 15 | 25747819699179668 |
| 16 | 899388184082559576 |
| 17 | 33613386298645020835 |
| 18 | 1338749843351681925409 |