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 | 7 |
| 3 | 23 |
| 4 | 203 |
| 5 | 1606 |
| 6 | 18435 |
| 7 | 221778 |
| 8 | 2773763 |
| 9 | 33297380 |
| 10 | 375158732 |
| 11 | 3907656327 |
| 12 | 37504171766 |
| 13 | 331785257145 |
| 14 | 2712509085687 |
| 15 | 20560611034067 |
| 16 | 144992583036707 |
| 17 | 954428916508309 |
| 18 | 5882732966056385 |
| 19 | 34048050206744705 |