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 | 5 |
| 3 | 13 |
| 4 | 73 |
| 5 | 281 |
| 6 | 1741 |
| 7 | 8485 |
| 8 | 57233 |
| 9 | 328753 |
| 10 | 2389141 |
| 11 | 15539261 |
| 12 | 120661465 |
| 13 | 866545993 |
| 14 | 7140942173 |
| 15 | 55667517781 |
| 16 | 484124048161 |
| 17 | 4046845186145 |
| 18 | 36967280461093 |
| 19 | 328340133863533 |
| 20 | 3137853448906601 |
| 21 | 29405064157989241 |