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 | 3 |
| 4 | 9 |
| 5 | 29 |
| 6 | 142 |
| 7 | 998 |
| 8 | 12145 |
| 9 | 273400 |
| 10 | 11991377 |
| 11 | 1018707920 |
| 12 | 165078860715 |
| 13 | 50500999728875 |
| 14 | 29053989521340327 |
| 15 | 31426435300576595334 |
| 16 | 64000986599534312456052 |
| 17 | 245935832697890955733422940 |
| 18 | 1787577661113111145804012336114 |
| 19 | 24637809007125076355873926288686728 |