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 | 2 |
| 2 | 3 |
| 3 | 4 |
| 4 | 9 |
| 5 | 24 |
| 6 | 75 |
| 7 | 252 |
| 8 | 903 |
| 9 | 3376 |
| 10 | 13068 |
| 11 | 51960 |
| 12 | 211222 |
| 13 | 874440 |
| 14 | 3676335 |
| 15 | 15660680 |
| 16 | 67474980 |
| 17 | 293617248 |
| 18 | 1288876879 |
| 19 | 5701688928 |
| 20 | 25397905302 |
| 21 | 113838544880 |
| 22 | 513117505278 |
| 23 | 2324638603980 |
| 24 | 10580591966824 |
| 25 | 48362627748240 |