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 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 28 |
| 4 | 203 |
| 5 | 1936 |
| 6 | 23517 |
| 7 | 349504 |
| 8 | 6149495 |
| 9 | 124999936 |
| 10 | 2881935953 |
| 11 | 74300836864 |
| 12 | 2118007738035 |
| 13 | 66142897770496 |
| 14 | 2245609694259557 |
| 15 | 82351536043343872 |
| 16 | 3244079458377786863 |
| 17 | 136619472483668525056 |
| 18 | 6125138252818308310041 |
| 19 | 291271111111111111081984 |