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 | 24 |
| 5 | 119 |
| 6 | 694 |
| 7 | 4579 |
| 8 | 33218 |
| 9 | 259483 |
| 10 | 2149558 |
| 11 | 18672277 |
| 12 | 168648090 |
| 13 | 1573625606 |
| 14 | 15093309024 |
| 15 | 148223240022 |
| 16 | 1485673163882 |
| 17 | 15159644212775 |
| 18 | 157142812302992 |
| 19 | 1651865171372967 |
| 20 | 17582693993265148 |
| 21 | 189269329080075275 |
| 22 | 2058215511081891400 |
| 23 | 22589841589522026553 |