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 | 2 |
| 3 | 6 |
| 4 | 23 |
| 5 | 109 |
| 6 | 619 |
| 7 | 4113 |
| 8 | 31352 |
| 9 | 269841 |
| 10 | 2589026 |
| 11 | 27404677 |
| 12 | 317265161 |
| 13 | 3988181568 |
| 14 | 54099618419 |
| 15 | 787705115000 |
| 16 | 12253696410675 |
| 17 | 202831037178017 |
| 18 | 3559585021719875 |
| 19 | 66018657264425355 |
| 20 | 1290284788431977106 |
| 21 | 26505045303122642171 |
| 22 | 570918508059059670322 |