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 | 2 |
| 3 | 3 |
| 4 | 16 |
| 5 | 85 |
| 6 | 696 |
| 7 | 6349 |
| 8 | 72080 |
| 9 | 918873 |
| 10 | 13484080 |
| 11 | 219335281 |
| 12 | 3962458248 |
| 13 | 78203547877 |
| 14 | 1680235050872 |
| 15 | 38958029188485 |
| 16 | 970681471597216 |
| 17 | 25847378934429361 |
| 18 | 732794687650764000 |
| 19 | 22032916968153975769 |
| 20 | 700360446794528578520 |