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 | 0 |
| 2 | 2 |
| 3 | 13 |
| 4 | 69 |
| 5 | 346 |
| 6 | 1700 |
| 7 | 8286 |
| 8 | 40264 |
| 9 | 195488 |
| 10 | 949302 |
| 11 | 4613025 |
| 12 | 22436997 |
| 13 | 109240038 |
| 14 | 532410060 |
| 15 | 2597468685 |
| 16 | 12684628125 |
| 17 | 62002335160 |
| 18 | 303332650190 |
| 19 | 1485213237135 |
| 20 | 7277719953415 |
| 21 | 35687662907750 |
| 22 | 175120787451540 |