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 | 1 |
| 3 | 3 |
| 4 | 7 |
| 5 | 25 |
| 6 | 105 |
| 7 | 547 |
| 8 | 3367 |
| 9 | 24033 |
| 10 | 195169 |
| 11 | 1777651 |
| 12 | 17950551 |
| 13 | 199059673 |
| 14 | 2405063017 |
| 15 | 31448531955 |
| 16 | 442501797655 |
| 17 | 6666753146497 |
| 18 | 107081325959937 |
| 19 | 1826636018849443 |
| 20 | 32980276187719399 |
| 21 | 628351055737088601 |